Lac operon. Medical search

The genetic unit consisting of three structural genes, an operator and a regulatory gene. The regulatory gene controls the synthesis of the three structural genes: BETA-GALACTOSIDASE and beta-galactoside permease (involved with the metabolism of lactose), and beta-thiogalactoside acetyltransferase.

In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.

A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry.

Bacterial repressor proteins that bind to the LAC OPERON and thereby prevent the synthesis of proteins involved in catabolism of LACTOSE. When lactose levels are high lac repressors undergo an allosteric change that causes their release from the DNA and the resumption of lac operon transcription.

A family of galactoside hydrolases that hydrolyze compounds with an O-galactosyl linkage. EC 3.2.1.-.

A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.

A non-metabolizable galactose analog that induces expression of the LAC OPERON.

A group of enzymes that catalyzes the hydrolysis of terminal, non-reducing beta-D-galactose residues in beta-galactosides. Deficiency of beta-Galactosidase A1 may cause GANGLIOSIDOSIS, GM1.

The interference in synthesis of an enzyme due to the elevated level of an effector substance, usually a metabolite, whose presence would cause depression of the gene responsible for enzyme synthesis.

Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.

The functional hereditary units of BACTERIA.

Includes ortho-, meta-, and para-nitrophenylgalactosides.

Proteins found in any species of bacterium.

A discipline concerned with studying biological phenomena in terms of the chemical and physical interactions of molecules.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

Proteins obtained from ESCHERICHIA COLI.

Deoxyribonucleic acid that makes up the genetic material of bacteria.

Genetic loci which direct transcription of ribosomal RNA in bacterial operons. They are designated rrnB, rrnC, rrnD, etc. according to the structural position of the transcription unit in the DNA sequence.

Genes which regulate or circumscribe the activity of other genes; specifically, genes which code for PROTEINS or RNAs which have GENE EXPRESSION REGULATION functions.

Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.

The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

A transcriptional regulator in prokaryotes which, when activated by binding cyclic AMP, acts at several promoters. Cyclic AMP receptor protein was originally identified as a catabolite gene activator protein. It was subsequently shown to regulate several functions unrelated to catabolism, and to be both a negative and a positive regulator of transcription. Cell surface cyclic AMP receptors are not included (CYCLIC AMP RECEPTORS), nor are the eukaryotic cytoplasmic cyclic AMP receptor proteins, which are the regulatory subunits of CYCLIC AMP-DEPENDENT PROTEIN KINASES.

The regulatory elements of an OPERON to which activators or repressors bind thereby effecting the transcription of GENES in the operon.

Galactosides in which the oxygen atom linking the sugar and aglycone is replaced by a sulfur atom.

Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.

Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.

A subdiscipline of genetics which deals with the genetic mechanisms and processes of microorganisms.

Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.

A temperate coliphage, in the genus Mu-like viruses, family MYOVIRIDAE, composed of a linear, double-stranded molecule of DNA, which is able to insert itself randomly at any point on the host chromosome. It frequently causes a mutation by interrupting the continuity of the bacterial OPERON at the site of insertion.

DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.

The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.

A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.

An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood.

A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.

Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.

An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis.

Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.

The transfer of bacterial DNA by phages from an infected bacterium to another bacterium. This also refers to the transfer of genes into eukaryotic cells by viruses. This naturally occurring process is routinely employed as a GENE TRANSFER TECHNIQUE.

Viruses whose host is Escherichia coli.

The meaning ascribed to the BASE SEQUENCE with respect to how it is translated into AMINO ACID SEQUENCE. The start, stop, and order of amino acids of a protein is specified by consecutive triplets of nucleotides called codons (CODON).

Any compound that contains a constituent sugar, in which the hydroxyl group attached to the first carbon is substituted by an alcoholic, phenolic, or other group. They are named specifically for the sugar contained, such as glucoside (glucose), pentoside (pentose), fructoside (fructose), etc. Upon hydrolysis, a sugar and nonsugar component (aglycone) are formed. (From Dorland, 28th ed; From Miall's Dictionary of Chemistry, 5th ed)

Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.

Biologically active DNA which has been formed by the in vitro joining of segments of DNA from different sources. It includes the recombination joint or edge of a heteroduplex region where two recombining DNA molecules are connected.

Any method used for determining the location of and relative distances between genes on a chromosome.

Enzymes that catalyze DNA template-directed extension of the 3'-end of an RNA strand one nucleotide at a time. They can initiate a chain de novo. In eukaryotes, three forms of the enzyme have been distinguished on the basis of sensitivity to alpha-amanitin, and the type of RNA synthesized. (From Enzyme Nomenclature, 1992).

The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.

Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.

The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.

A species of gram-positive bacteria that is a common soil and water saprophyte.

Processes that incorporate some element of randomness, used particularly to refer to a time series of random variables.

A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.

The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.

Use of restriction endonucleases to analyze and generate a physical map of genomes, genes, or other segments of DNA.

Plasmids which determine the ability of a bacterium to ferment lactose.

A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.

Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.

An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.

Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.

Mutagenesis where the mutation is caused by the introduction of foreign DNA sequences into a gene or extragenic sequence. This may occur spontaneously in vivo or be experimentally induced in vivo or in vitro. Proviral DNA insertions into or adjacent to a cellular proto-oncogene can interrupt GENETIC TRANSLATION of the coding sequences or interfere with recognition of regulatory elements and cause unregulated expression of the proto-oncogene resulting in tumor formation.

The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.

The rate dynamics in chemical or physical systems.

A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.

Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.

An ascomycetous yeast of the fungal family Saccharomycetaceae, order SACCHAROMYCETALES.

A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed)

Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1.

In eukaryotes, a genetic unit consisting of a noncontiguous group of genes under the control of a single regulator gene. In bacteria, regulons are global regulatory systems involved in the interplay of pleiotropic regulatory domains and consist of several OPERONS.

A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).

A parasexual process in BACTERIA; ALGAE; FUNGI; and ciliate EUKARYOTA for achieving exchange of chromosome material during fusion of two cells. In bacteria, this is a uni-directional transfer of genetic material; in protozoa it is a bi-directional exchange. In algae and fungi, it is a form of sexual reproduction, with the union of male and female gametes.

The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.

The genetic complement of a BACTERIA as represented in its DNA.

A copper-containing oxidoreductase enzyme that catalyzes the oxidation of 4-benzenediol to 4-benzosemiquinone. It also has activity towards a variety of O-quinols and P-quinols. It primarily found in FUNGI and is involved in LIGNIN degradation, pigment biosynthesis and detoxification of lignin-derived products.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.

A protein which is a subunit of RNA polymerase. It effects initiation of specific RNA chains from DNA.

DNA sequences recognized as signals to end GENETIC TRANSCRIPTION.

Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.

A plasmid whose presence in the cell, either extrachromosomal or integrated into the BACTERIAL CHROMOSOME, determines the "sex" of the bacterium, host chromosome mobilization, transfer via conjugation (CONJUGATION, GENETIC) of genetic material, and the formation of SEX PILI.

A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.

The in vitro fusion of GENES by RECOMBINANT DNA techniques to analyze protein behavior or GENE EXPRESSION REGULATION, or to merge protein functions for specific medical or industrial uses.

An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.

A serotype of the species California encephalitis virus (ENCEPHALITIS VIRUS, CALIFORNIA), in the genus ORTHOBUNYAVIRUS, causing human MENINGOENCEPHALITIS. This is the agent most responsible for California encephalitis (ENCEPHALITIS, CALIFORNIA), the most prevalent mosquito-borne disease recognized in the United States.

The bacterial sugar phosphotransferase system (PTS) that catalyzes the transfer of the phosphoryl group from phosphoenolpyruvate to its sugar substrates (the PTS sugars) concomitant with the translocation of these sugars across the bacterial membrane. The phosphorylation of a given sugar requires four proteins, two general proteins, Enzyme I and HPr and a pair of sugar-specific proteins designated as the Enzyme II complex. The PTS has also been implicated in the induction of synthesis of some catabolic enzyme systems required for the utilization of sugars that are not substrates of the PTS as well as the regulation of the activity of ADENYLYL CYCLASES. EC 2.7.1.-.

Computer-based representation of physical systems and phenomena such as chemical processes.

A species of gram-negative, aerobic bacteria isolated from soil and water as well as clinical specimens. Occasionally it is an opportunistic pathogen.

An enzyme that catalyzes the conversion of L-tryptophan and water to indole, pyruvate, and ammonia. It is a pyridoxal-phosphate protein, requiring K+. It also catalyzes 2,3-elimination and beta-replacement reactions of some indole-substituted tryptophan analogs of L-cysteine, L-serine, and other 3-substituted amino acids. (From Enzyme Nomenclature, 1992) EC 4.1.99.1.

Transcriptional repression by the Drosophila giant protein: cis element positioning provides an alternative means of interpreting an effector gradient. (1/2991)

Early developmental patterning of the Drosophila embryo is driven by the activities of a diverse set of maternally and zygotically derived transcription factors, including repressors encoded by gap genes such as Kruppel, knirps, giant and the mesoderm-specific snail. The mechanism of repression by gap transcription factors is not well understood at a molecular level. Initial characterization of these transcription factors suggests that they act as short-range repressors, interfering with the activity of enhancer or promoter elements 50 to 100 bp away. To better understand the molecular mechanism of short-range repression, we have investigated the properties of the Giant gap protein. We tested the ability of endogenous Giant to repress when bound close to the transcriptional initiation site and found that Giant effectively represses a heterologous promoter when binding sites are located at -55 bp with respect to the start of transcription. Consistent with its role as a short-range repressor, as the binding sites are moved to more distal locations, repression is diminished. Rather than exhibiting a sharp 'step-function' drop-off in activity, however, repression is progressively restricted to areas of highest Giant concentration. Less than a two-fold difference in Giant protein concentration is sufficient to determine a change in transcriptional status of a target gene. This effect demonstrates that Giant protein gradients can be differentially interpreted by target promoters, depending on the exact location of the Giant binding sites within the gene. Thus, in addition to binding site affinity and number, cis element positioning within a promoter can affect the response of a gene to a repressor gradient. We also demonstrate that a chimeric Gal4-Giant protein lacking the basic/zipper domain can specifically repress reporter genes, suggesting that the Giant effector domain is an autonomous repression domain. (+info)

Accelerated accumulation of somatic mutations in mice deficient in the nucleotide excision repair gene XPA. (2/2991)

Inheritable mutations in nucleotide excision repair (NER) genes cause cancer-prone human disorders, such as xeroderma pigmentosum, which are also characterized by symptoms of accelerated ageing. To study the impact of NER deficiency on mutation accumulation in vivo, mutant frequencies have been determined in liver and brain of 2-16 month old NER deficient XPA-/-, lacZ hybrid mice. While mutant frequencies in liver of 2-month old XPA-/-, lacZ mice were comparable to XPA+/-, lacZ and the lacZ parental strain animals, by 4 months of age mutant frequencies in the XPA-deficient mice were significantly increased by a factor of two and increased further until the age of 16 months. In brain, mutant frequencies were not found to increase with age. These results show that a deficiency in the NER gene XPA causes an accelerated accumulation of somatic mutations in liver but not in brain. This is in keeping with a higher incidence of spontaneous liver tumors reported earlier for XPA-/- mice after about 15 months of age. (+info)

Adenoviral gene transfer into the normal and injured spinal cord: enhanced transgene stability by combined administration of temperature-sensitive virus and transient immune blockade. (3/2991)

This study characterized gene transfer into both normal and injured adult rat dorsal spinal cord using first (E1-/E3-) or second (E1-/E2A125/E3-, temperature-sensitive; ts) generation of replication-defective adenoviral (Ad) vectors. A novel immunosuppressive regimen aimed at blocking CD4/CD45 lymphocytic receptors was tested for improving transgene persistence. In addition, the effect of gene transfer on nociception was also evaluated. Seven days after treatment, numerous LacZ-positive cells were observed after transfection with either viral vector. By 21 days after transfection, beta-galactosidase staining was reduced and suggestive of ongoing cytopathology in both Ad-treated groups, despite the fact that the immunogenicity of LacZ/Adts appeared less when compared with that elicited by the LacZ/Ad vector. In contrast, immunosuppressed animals showed a significant (P < or = 0.05) increase in the number of LacZ-positive cells not displaying cytopathology. In these animals, a concomitant reduction in numbers of macrophages/microglia and CD4 and CD8 lymphocytes was observed. Only animals that received LacZ/Adts and immunosuppression showed transgene expression after 60 days. Similar results were observed in animals in which the L4-L5 dorsal roots were lesioned before transfection. Gene transfer into the dorsal spinal cord did not affect nociception, independent of the adenovirus vector. These results indicate that immune blockade of the CD4/CD45 lymphocytic receptors enhanced transgene stability in adult animals with normal or injured spinal cords and that persistent transgene expression in the spinal cord does not interfere with normal neural function. (+info)

Transduction of glioma cells using a high-titer retroviral vector system and their subsequent migration in brain tumors. (4/2991)

The intracranial migration of transduced glioma cells was investigated in order to improve the treatment of malignant glioma by gene therapy using retroviral vectors. In this study, about half the volume of the tumor mass could be transduced in 14 days after only a single implantation of 3 x 10(5) retrovirus-producing cells into a tumor mass with a diameter of 5 mm. Moreover, we were able to follow the migration of glioma cells transduced by the lacZ-harboring retroviruses originating from the high-titer retrovirus-producing cells. Besides the importance of using a high-titer retroviral vector system, our results also indicate that the implantation site of the virus-producing cells and the interval between the implantation of the virus-producing cells and the subsequent administration of ganciclovir are important factors for the efficient killing of glioma cells. (+info)

Murine matrix metalloproteinase 9 gene. 5'-upstream region contains cis-acting elements for expression in osteoclasts and migrating keratinocytes in transgenic mice. (5/2991)

Knowledge about the regulation of cell lineage-specific expression of extracellular matrix metalloproteinases is limited. In the present work, the murine matrix metalloproteinase 9 (MMP-9) gene was shown to contain 13 exons, and the 2.8-kilobase pair upstream region was found to contain several common promoter elements including a TATA box-like motif, three GC boxes, four AP-1-like binding sites, an AP-2 site, and three PEA3 consensus sequences that may be important for basic activity of the gene. In order to identify cell-specific regulatory elements, constructs containing varying lengths of the upstream region in front of a LacZ reporter gene were made and studied for expression in transgenic mice generated by microinjection into fertilized oocytes. Analyses of the mice revealed that the presence of sequences between -2722 and -7745 allowed for expression in osteoclasts and migrating keratinocytes, i. e. cells that have been shown to normally express the enzyme in vivo. The results represent the first in vivo demonstration of the location of cell-specific control elements in a matrix metalloproteinase gene and show that element(s) regulating most cell-specific activities of 92-kDa type collagenase are located in the -2722 to -7745 base pair region. (+info)

Reduced differentiation potential of primary MyoD-/- myogenic cells derived from adult skeletal muscle. (6/2991)

To gain insight into the regeneration deficit of MyoD-/- muscle, we investigated the growth and differentiation of cultured MyoD-/- myogenic cells. Primary MyoD-/- myogenic cells exhibited a stellate morphology distinct from the compact morphology of wild-type myoblasts, and expressed c-met, a receptor tyrosine kinase expressed in satellite cells. However, MyoD-/- myogenic cells did not express desmin, an intermediate filament protein typically expressed in cultured myoblasts in vitro and myogenic precursor cells in vivo. Northern analysis indicated that proliferating MyoD-/- myogenic cells expressed fourfold higher levels of Myf-5 and sixfold higher levels of PEA3, an ETS-domain transcription factor expressed in newly activated satellite cells. Under conditions that normally induce differentiation, MyoD-/- cells continued to proliferate and with delayed kinetics yielded reduced numbers of predominantly mononuclear myocytes. Northern analysis revealed delayed induction of myogenin, MRF4, and other differentiation-specific markers although p21 was upregulated normally. Expression of M-cadherin mRNA was severely decreased whereas expression of IGF-1 was markedly increased in MyoD-/- myogenic cells. Mixing of lacZ-labeled MyoD-/- cells and wild-type myoblasts revealed a strict autonomy in differentiation potential. Transfection of a MyoD-expression cassette restored cytomorphology and rescued the differentiation deficit. We interpret these data to suggest that MyoD-/- myogenic cells represent an intermediate stage between a quiescent satellite cell and a myogenic precursor cell. (+info)

Efflux-mediated aminoglycoside and macrolide resistance in Burkholderia pseudomallei. (7/2991)

Burkholderia pseudomallei, the causative agent of melioidosis, is intrinsically resistant to a wide range of antimicrobial agents including beta-lactams, aminoglycosides, macrolides, and polymyxins. We used Tn5-OT182 to mutagenize B. pseudomallei to identify the genes involved in aminoglycoside resistance. We report here on the identification of AmrAB-OprA, a multidrug efflux system in B. pseudomallei which is specific for both aminoglycoside and macrolide antibiotics. We isolated two transposon mutants, RM101 and RM102, which had 8- to 128-fold increases in their susceptibilities to the aminoglycosides streptomycin, gentamicin, neomycin, tobramycin, kanamycin, and spectinomycin. In addition, both mutants, in contrast to the parent, were susceptible to the macrolides erythromycin and clarithromycin but not to the lincosamide clindamycin. Sequencing of the DNA flanking the transposon insertions revealed a putative operon consisting of a resistance, nodulation, division-type transporter, a membrane fusion protein, an outer membrane protein, and a divergently transcribed regulatorprotein. Consistent with the presence of an efflux system, both mutants accumulated [3H] dihydro streptomycin, whereas the parent strain did not. We constructed an amr deletion strain, B. pseudomallei DD503, which was hypersusceptible to aminoglycosides and macrolides and which was used successfully in allelic exchange experiments. These results suggest that an efflux system is a major contributor to the inherent high-level aminoglycoside and macrolide resistance found in B. pseudomallei. (+info)

Aging-specific expression of Drosophila hsp22. (8/2991)

hsp22 is among the least abundantly expressed Drosophila heat shock (hs) genes during both development and heat stress. In contrast, hsp22 was found to be the most abundantly expressed hs gene during Drosophila aging. During aging, hsp22 RNA was induced 60-fold in the head, with somewhat lower level induction in abdomen and thorax. Induction of the other hs gene RNAs was 150-fold, with particularly abundant expression in eye tissue. Aging-specific induction of hsp22 was reproduced by hsp22:lacZ fusion reporter constructs in transgenic flies. Analysis of specific promoter mutations in transgenic flies indicated that functional heat shock response elements are required for hsp22 induction during aging. Finally, comparison of hsp22 RNA and protein expression patterns suggests that aging-specific expression of hsp22 is regulated at both the transcriptional and the posttranscriptional levels. Aging-specific induction of hsp22 is discussed with regard to current evolutionary theories of aging. (+info)

... lac operon in NCBI Bookshelf [2] Virtual Cell Animation Collection Introducing: The Lac Operon The lac Operon: Bozeman Science ... The lactose operon (lac operon) is an operon required for the transport and metabolism of lactose in E. coli and many other ... "Induction of the lac operon in E. coli" (PDF). SAPS. Retrieved 29 June 2016. Lac+Operon at the US National Library of Medicine ... In the absence of lactose, the lac repressor, lacI, halts production of the enzymes encoded by the lac operon. The lac ...

https://en.wikipedia.org/wiki/Lac_operon

The gal operon is also controlled by CRP-cAMP, similarly to the lac operon. CRP-cAMP binds to the -35 region, promoting ... lac operon Weickert, M. J.; Adhya, S. (October 1993). "The galactose regulon of Escherichia coli". Molecular Microbiology. 10 ( ... The gal operon is a prokaryotic operon, which encodes enzymes necessary for galactose metabolism. Repression of gene expression ... The gal operon contains two operators, OE (for external) and OI (for internal). The former is just upstream of the promoter, ...

https://en.wikipedia.org/wiki/Gal_operon

gene regulation Operon lac operon Navarro, Clarisse; Wu, Long-Fei; Mandrand-Berthelot, Marie-Andrée (1 September 1993). "The ... The nik operon is an operon required for uptake of nickel ions into the cell. It is present in many bacteria, but has been ... Nickel ion concentration in the cell is regulated through the nik operon. The nik operon consists of six genes. The first five ... The following table summarizes the structure of the nik operon: Regulation of expression of the nikR gene is achieved by two ...

https://en.wikipedia.org/wiki/Nik_operon

It is coded for by the lacA gene of the lac operon in E. coli. It catalyzes the following reaction: acetyl-CoA + beta-D- ... The enzyme's role in the classical E.coli lac operon remains unclear. However, the enzyme's cellular role may be to detoxify ... Transacetylase Wang XG, Olsen LR, Roderick SL (April 2002). "Structure of the lac operon galactoside acetyltransferase". ... Roderick SL (June 2005). "The lac operon galactoside acetyltransferase". Comptes Rendus Biologies. 328 (6): 568-75. doi:10.1016 ...

https://en.wikipedia.org/wiki/Galactoside_acetyltransferase

... lac operon Klar AJ, Halvorson HO (1974). "Studies on the positive regulatory gene, GAL4, in regulation of galactose catabolic ...

https://en.wikipedia.org/wiki/Gal4_transcription_factor

... the lac operon is repressed. This is because glucose actively prevents the induction of lacZYA. In the ara operon, arabinose is ... The inducer in the lac operon is allolactose. If lactose is present in the medium, then a small amount of it will be converted ... The lactose operon is one example of an inducible system. Repressor proteins bind to the DNA strand and prevent RNA polymerase ... RNA polymerase can then begin to transcribe operon genes. By binding to activators. Activators generally bind poorly to ...

https://en.wikipedia.org/wiki/Inducer

This allows for expression of the operon. The lac operon is a negatively controlled inducible operon, where the inducer ... The first operon to be described was the lac operon in E. coli. The 1965 Nobel Prize in Physiology and Medicine was awarded to ... The lac operon of the model bacterium Escherichia coli was the first operon to be discovered and provides a typical example of ... While the lac operon can be activated by a chemical (allolactose), the tryptophan (Trp) operon is inhibited by a chemical ( ...

https://en.wikipedia.org/wiki/Operon

X-gal plates are differential for lac operon mutants. Transport media should fulfill these criteria: Temporary storage of ...

https://en.wikipedia.org/wiki/Growth_medium

Lac operon Fischer L, Scheckermann C, Wagner F (April 1995). "Purification and characterization of a thermotolerant beta- ...

https://en.wikipedia.org/wiki/Phenyl-D-galactopyranoside

Model of Lac Operon The SGC protein browser SILVA database of aligned rRNA sequence data Barcode of Life database of COI ... This is best illustrated by the well-studied lac operon, in which three structural genes (lacZ, lacY, and lacA) are all ... Müller-Hill, Benno (1996-01-01). The Lac Operon: A Short History of a Genetic Paradigm. Walter de Gruyter. ISBN 9783110148305. ... The distinction between regulatory and structural genes can be attributed to the original 1959 work on Lac operon protein ...

https://en.wikipedia.org/wiki/Structural_gene

Lac operon Schumacher MA, Choi KY, Zalkin H, Brennan RG (November 1994). "Crystal structure of LacI member, PurR, bound to DNA ... They showed that in vitro the protein bound to DNA containing the lac operon, and it released the DNA when IPTG (an analog of ... Oehler S, Eismann ER, Krämer H, Müller-Hill B (April 1990). "The three operators of the lac operon cooperate in repression". ... Goodsell DS (2003). "Lac Repressor". RCSB Protein Data Bank. doi:10.2210/rcsb_pdb/mom_2003_3. Lewis M (June 2005). "The lac ...

https://en.wikipedia.org/wiki/Lac_repressor

72 Müller-Hill, Benno (1996). The lac Operon : a short history of a genetic paradigm. New York: Walter de Gruyter. ISBN 978-3- ... They hoped to mix E. coli lac repressor with lac operator, crystallize it, and examine the protein-DNA binding of the crystals ... the lambda repressor and the lac repressor. Riggs worked on isolating the lac repressor by affinity chromatography. Walter ... They were able to clone Itakura's lac operator and confirm that it would work in live bacteria, an important result. They also ...

https://en.wikipedia.org/wiki/Arthur_Riggs_(geneticist)

... when the repressor is inactive transcription of the operon can occur (see e.g. Lac operon). The products of operon genes ... The regulation of lactose metabolism genes in E. coli (lac operon) was the first such mechanism to be described in 1961. A ... The genes in an operon are transcribed as a continuous messenger RNA, referred to as a polycistronic mRNA. The term cistron in ... The transcription of an operon's mRNA is often controlled by a repressor that can occur in an active or inactive state ...

https://en.wikipedia.org/wiki/Gene

The latter is produced by the lac operon in Escherichia coli.[citation needed] In nature, lactose is found primarily in milk ...

https://en.wikipedia.org/wiki/Galactose

It is encoded by the lacY gene in the lac operon. The sugar lies in the hydrophilic core of the protein which is accessible ...

https://en.wikipedia.org/wiki/Lactose_permease

Newton, W. A.; Beckwith, J. R.; Zipser, D. & Brenner, S. (1965). "Nonsense mutants and polarity in the lac operon of ... Elgamal, S.; Artsimovitch, I.; Ibba, M. & Brenner, S. (1965). "Nonsense mutants and polarity in the lac operon of Escherichia ... The term "attenuation" was introduced to describe the his operon. While it is typically used to describe biosynthesis operons ... The trp operon is regulated by both attenuation and repression, and was the first evidence that gene expression regulation ...

https://en.wikipedia.org/wiki/Transcription-translation_coupling

The cell "prefers" glucose, and, if it is available, the lac operon is not activated, even when lactose is present. This is an ... cAMP-CAP is required for transcription activation of the lac operon. This requirement reflects the greater simplicity with ...

https://en.wikipedia.org/wiki/Catabolite_activator_protein

The lac operon is used in the biotechnology industry for production of recombinant proteins for therapeutic use. The gene or ... The first natural gene circuit studied in detail was the lac operon. In studies of diauxic growth of E. coli on two-sugar media ... function was a two-part control mechanism on the lac operon. When lactose is present in the cell the enzyme β-galactosidase is ... When lactose is absent in the cell the lac repressor inhibits the production of the enzyme β-galactosidase to prevent any ...

https://en.wikipedia.org/wiki/Synthetic_biological_circuit

A classic example of positive feedback is the lac operon in E. coli. Positive feedback plays an integral role in cellular ...

https://en.wikipedia.org/wiki/Positive_feedback

Monod later put aside his work on diauxic growth and focused on the lac operon model of gene expression, which led to a Nobel ... During his work on the lac operon of E. coli, Joshua Lederberg isolated β-galactosidase and found it in greater quantities in ... Thus, if glucose is present, cAMP levels remain low, so CAP is unable to activate transcription of the lac operon, regardless ... This process can also refer to the positive control of the lac operon. Editors, AccessScience (2015). "Diauxic growth (diauxie ...

https://en.wikipedia.org/wiki/Diauxic_growth

cAMP, for example, is involved in the positive regulation of the lac operon. In an environment with a low glucose concentration ... With a high glucose concentration, the cAMP concentration decreases, and the CRP disengages from the lac operon. Since cyclic ... making it easier for RNA polymerase to bind to the adjacent promoter to start transcription of the lac operon, increasing the ... The protein assumes its active shape and binds to a specific site upstream of the lac promoter, ...

https://en.wikipedia.org/wiki/Cyclic_adenosine_monophosphate

Lac operon Lactic acid Lactose intolerance Nectar Sugars in wine Peter M. Collins (2006). Dictionary of Carbohydrates (2nd ed ... Lactose makes up around 2-8% of milk (by mass). The name comes from lac (gen. lactis), the Latin word for milk, plus the suffix ...

https://en.wikipedia.org/wiki/Lactose

The Lac operon is an interesting example of how gene expression can be regulated. Viruses, despite having only a few genes, ... The image to the right demonstrates regulation by a repressor in the lac operon. General transcription factors position RNA ... the first discovery of a gene regulation system is widely considered to be the identification in 1961 of the lac operon, ...

https://en.wikipedia.org/wiki/Regulation_of_gene_expression

Other strong promoters used include Trp promoter and Tac-Promoter, which are a hybrid of both the Trp and Lac Operon promoters ... Promoter - commonly used inducible promoters are promoters derived from lac operon and the T7 promoter. ...

https://en.wikipedia.org/wiki/Vector_(molecular_biology)

An example of a cis-acting regulatory sequence is the operator in the lac operon. This DNA sequence is bound by the lac ... The lac operator is, thus, considered to "act in cis" on the regulation of the nearby genes. The operator itself does not code ... Operators are CREs in prokaryotes and some eukaryotes that exist within operons, where they can bind proteins called repressors ... mRNA Other Regulation of gene expression Cis-trans isomerism Gene regulatory network Operon Promoter Trans-acting factor Rfam ...

https://en.wikipedia.org/wiki/Cis-regulatory_element

Previous studies had only shown success in the lac operon, but the lambda phage was successful for the arabinose operon in her ... Their work involved studying the lac operon to further understand the E. coli arabinose operon. From their research, they were ... able to show that a transducing bacteriophage could work for the arabinose operon. ...

https://en.wikipedia.org/wiki/Susan_Gottesman

β-galactosidase is a protein encoded by the lacZ gene of the lac operon, and it exists as a homotetramer in its active state. ... It should also be understood that the lac operon is affected by the presence of glucose. The protein EIIAGlc, which is involved ... Isopropyl β-D-1-thiogalactopyranoside (IPTG), which functions as the inducer of the lac operon, may be used in the media to ... Insertion of a HindII fragment of the lac regulatory region in M13 replicative form in vitro". Proceedings of the National ...

https://en.wikipedia.org/wiki/Blue–white_screen

cAMP binds to catabolite activator protein (CAP) and together they will bind to a promoter sequence on the lac operon. However ... Next, bacteria start to transcribe the lac operon and produce β-galactosidase enzymes for lactose metabolism. The example above ... In this alternative pathway CcpA negatively represses other sugar operons so they are off in the presence of glucose. It works ... and when Hpr is phosphoralated it can then allow CcpA to block transcription of the alternative sugar pathway operons at their ...

https://en.wikipedia.org/wiki/Catabolite_repression

"Exogenous Induction of the Escherichia coli Hexose Phosphate Transport System Defined by uhp-lac Operon Fusions". Journal of ...

https://en.wikipedia.org/wiki/Hexose_phosphate_uptake

... is normally used in molecular biology to induce the lac operon. Inducer Lac operon § Regulation by allolactose Lac repressor ... thereby dissociating it from the lac operator. The absence of the repressor allows the transcription of the lac operon to ... It is an inducer of the lac operon in Escherichia coli and many other enteric bacteria. It binds to a subunit of the tetrameric ... lac repressor, which results in conformational changes and reduces the binding affinity of the lac repressor to the lac ...

https://en.wikipedia.org/wiki/Allolactose

... and the lac operon, showing that the environment and genetic switches together control gene expression. He introduces the evo- ...

https://en.wikipedia.org/wiki/Endless_Forms_Most_Beautiful_(book)

... meaning that besides the lac promoter, the lac operon is also present. If the lac operator were not present the IPTG would not ... When referring to a promoter some authors actually mean promoter + operator; i.e., the lac promoter is IPTG inducible, ... Activator (genetics) Enhancer (genetics) Glossary of gene expression terms Operon Regulation of gene expression Repressor ...

https://en.wikipedia.org/wiki/Promoter_(genetics)

... and lac(z) respectively (stated in the fifth and sixth rule of the program), in a cluster of genes (lac(X)) - called an operon ... lac(X)) :- amount(glucose, medium), amount(lactose, medium). code(lac(y), permease). code(lac(z), galactosidase). temperature( ... lac(X)) :- amount(glucose, low), amount(lactose, hi). express( ...

https://en.wikipedia.org/wiki/Abductive_logic_programming

... and the lac operon and other inducible systems in bacteria. The focus of Dobrogosz's research shifted in 1985, when he and ...

https://en.wikipedia.org/wiki/Walter_Dobrogosz

For example, the ste11 transcript in Schizosaccharomyces pombe has a 2273 nucleotide 5′ UTR while the lac operon in Escherichia ...

https://en.wikipedia.org/wiki/Five_prime_untranslated_region

... may refer to: Los Angeles, California, the second most populous city in the US lacA, a structural gene in the lac operon ...

https://en.wikipedia.org/wiki/LACA

... in the lac repressor family. Boos, W; Shuman, H (March 1998). "Maltose/maltodextrin system of Escherichia coli: transport, ... where it is classically described as a group of ten genes in multiple operons whose expression is regulated by a single ...

https://en.wikipedia.org/wiki/Mal_regulon

15 three years prior to the isolation of the bacterial lac operon, and is noted as a key piece of evidence in establishing the ... three years before the successful isolation of the lac operon. He is also recognized for one of the earliest discoveries of a ...

https://en.wikipedia.org/wiki/Max_Birnstiel

This test uses an operon fusion placing the lac operon (responsible for producing β-galactosidase, a protein which degrades ... It is based on the ability of DNA-damaging agents to induce the expression of the umu operon. In connection with the damage ...

https://en.wikipedia.org/wiki/Umu_Chromotest

A 700-1400 base pair segment of DNA was found to have inserted itself into the gal and lac operons resulting in a strong polar ...

https://en.wikipedia.org/wiki/Illegitimate_recombination

... coli lac operon, which encodes proteins necessary for the transport and breakdown of the sugar lactose (lac). From their own ... In their model, the manufacture of proteins, such as the ones encoded within the lac (lactose) operon, is prevented when a ... Monod's interest in the lac operon originated from his doctoral dissertation, which explored the growth of bacteria on mixtures ... described in the Lac operon article) that was discovered by Jacob and Monod is fundamental to cellular regulation for all ...

https://en.wikipedia.org/wiki/Jacques_Monod

It also contributed to the development of the early repression model of gene regulation that explained how the lac operon and λ ...

https://en.wikipedia.org/wiki/Zygotic_induction

François Jacob and Jacques Monod followed the 1959 PaJaMo experiment with a series of publications regarding the lac operon ...

https://en.wikipedia.org/wiki/History_of_biology

... in the context of the lac operon of Escherichia coli. In the absence of lactose, the constitutively expressed lac repressor ... When present, lactose binds to the lac repressor, causing it to separate from the DNA and thereby enabling transcription to ... protein binds to the operator region of the DNA and prevents the transcription of the operon genes. ...

https://en.wikipedia.org/wiki/Enzyme_induction_and_inhibition

Galactoside permease is a protein coded by the lacY gene of the lac operon, and is found bound to the membrane of a cell for ...

https://en.wikipedia.org/wiki/Beta-galactoside_permease

"Mike's work has done for animal development what the work on the lac operon and phage lambda did for understanding gene ...

https://en.wikipedia.org/wiki/Michael_Levine_(biologist)

... produced from the combination of promoters from the trp and lac operons. It is commonly used for protein production in ... In contrast to the trp and the lac UV5 promoters, the tacI promoter has not only a consensus -35 sequence but also a consensus ... The tac promoter consists of the '-35' region of the trp promoter and the '-10' region of the lac promoter (and differs from a ... These hybrid promoters, tacI and tacII, were derived from sequences of the trp and the lac UV5 promoters. In the first hybrid ...

https://en.wikipedia.org/wiki/Tac-Promoter

In 1961, Jacques Monod, Jean-Pierre Changeux and François Jacob discovered the lac operon in the bacterium Escherichia coli. It ...

https://en.wikipedia.org/wiki/Evolutionary_developmental_biology

... such as lac operon coding for the proteins involved in breaking down lactose. Lactocillin is made by biosynthetic gene cluster ... Operons can code for a specific molecule, similar to BGC's, or other things such as associated proteins that work together in a ... Biosynthetic gene clusters are similar to operons in bacteria in that they both code for proteins that function together in a ... However, biosynthetic gene clusters always code for a known secondary metabolite, while operons are a general group of genes ...

https://en.wikipedia.org/wiki/Lactocillin

... see Lac operon for details) the number of bacteria present in a nutrient-containing broth was measured during the course of an ...

https://en.wikipedia.org/wiki/Growth_curve_(biology)

Repressor (see Lac repressor) and activator proteins are used to create genetic operons, which were identified by François ...

https://en.wikipedia.org/wiki/Feedback

... operon MeSH G14.340.024.686.545 - lac operon MeSH G14.340.024.686.645 - operator regions (genetics) MeSH G14.340.024.686.817 - ... operon MeSH G14.340.300.500.545 - lac operon MeSH G14.340.300.500.645 - operator regions (genetics) MeSH G14.340.300.500.817 - ... rrna operon MeSH G14.340.325.500 - genes, fungal MeSH G14.340.325.500.089 - genes, mating type, fungal MeSH G14.340.337.500 - ... rrna operon MeSH G14.340.024.742 - regulon MeSH G14.340.024.745 - replicon MeSH G14.340.024.745.725 - replication origin MeSH ...

https://en.wikipedia.org/wiki/List_of_MeSH_codes_(G14)

So, we call it the Jacob Monod lac operon. And the lac stands for the word lactose and the lac operon is found in the bacteria ... Okay, so what is this lac operon? So, before we talk about the details, the lac operon has a couple of genes that will make ... And the lac z, lac y, and lac a genes are all each going to code for an enzyme that helps in the breakdown of lactose, or in ... But, these three genes, this here is the lac z gene. This is the lac y gene, and this is the lac a gene. And so if you recall, ...

https://www.khanacademy.org/test-prep/mcat/biomolecules/dna/v/jacob-monod-lac-operon

The graphics illustrate how the operons are turned on and off depending on food sources. ... Students examine graphics showing the lac-operon and the trp operon. ... Lac Operon. On the second page of the document, students compare the lac operon to the trp operon. In this case, the operon is ... The lac-operon is an inducible operon. That means, it is turned on when lactose is present in the environment. Bacteria do not ...

https://www.biologycorner.com/2022/04/10/gene-regulation-in-prokaryotes-lac-operon/

Lac Operon, GMR, Genetics and Molecular Research ...

https://www.geneticsmr.org/keywords/lac-operon

Video explaining The Lac Operon for Microbiology. This is one of many videos provided by Clutch Prep to prepare you to succeed ... Review of the Lac Operon & Trp Operon. 11 mins. 0 completed. Learn ... Practice: The protein that binds to the operator of the lac operon to prevent transcription is encoded by which gene? ...

https://clutchprep.com/microbiology/the-lac-operon-Bio-1/67864/learn/28087

... operon from observed data by means of genetic programming ... automatic creation of a genetic network for the lac ... Automatic creation of a genetic network for the lac operon from observed data by means of genetic programming Created by W. ... title = "Automatic creation of a genetic network for the lac operon from observed data by means of genetic programming", * ... keywords = "genetic algorithms, genetic programming, Biology, genetic networks, reverse engineering, lac operon", * URL = ". ...

http://gpbib.pmacs.upenn.edu/gp-html/lanza_2000_ICSB.html

I would appreciate it someone could explain clearly how the genes in the lac operon of E coli are activated to allow the ... Figure 4.1.3. Induction of the lac operon by derepression.. The Lac Operon. Jacob and Monod proposed the lac operon model to ... the lac operon was one of the first examples of transcription regulation every studied. lacI is not in the lac operon, but it ... the gene products from the lac operon are not needed. Thus a regulatory factor, the repressor protein, prevents lac operon ...

https://gb.dualjuridik.org/4116-what-is-the-significance-of-and-biological-mechanism.html

BIOB11H3 Study Guide - Midterm Guide: Lac Operon, Lac Repressor, Beta-Galactosidase. byzantiumweasel548 ... BIOB11H3 Lecture Notes - Lecture 9: Lac Repressor, Lac Operon, Camp Receptor Protein. ... Binding of lactose to lac repressor is transient, Repressor now able to bind to operator. Cis (cid:448)s t(cid:396)a(cid:374)s ... will be inactivated when bound to lac. When lactose is present, it binds to repressor and inactivate it. Translation of mrna ...

https://oneclass.com/class-notes/ca/utsc/bio/biob-11h3/1390600-biob11h3-lecture-9.en.html

Lac Operon * Male * Mice * Mice, Inbred C57BL * Mice, Inbred DBA * Mice, Transgenic ...

https://pubmed.ncbi.nlm.nih.gov/19863697/

Which enzyme will be produced in a cell where a nonsense mutation is present in the lac operon? ... If nonsense mutation takes place in the lac y, lac z or lac a gene, the mRNA of the gene in which the mutation has occured, ... If the nonsense mutation takes place at the operator, then simultaneous constitutivity for all the products of the operon will ... If nonsense mutation occurs in all of the three genes, then no lac enzymes will be formed. ...

https://www.bartleby.com/affiliate/questions-and-answers/science/biology/cell-biology

Kennell, D. & Riezman, H. Transcription and translation initiation frequencies of the Escherichia coli lac operon. J. Mol. Biol ...

https://www.nature.com/articles/nature04599?error=cookies_not_supported&code=509a0c6f-a2da-4bad-a054-9f4d936854c1

... lacZ and lacY are deleted in strain 229/11. The lack of a functional lac operon has been associated with pathogenicity ... In Sd197 and Ss046 (late lactose-fermenting strains), the key gene, lacZ (encoding β-. d. -galactosidase) is intact, although ... H7 is most likely multifactorial and results from a novel combination of lack of cadA and lacZ expression and the presence of ... lacY (encoding galactose permease) is a pseudogene (12). Like Sf301 and Sb227, ...

https://wwwnc.cdc.gov/eid/article/19/8/13-0016

36.3 The lac Operon Illustrates the Control of Bacterial Gene Expression An Operon Consists of Regulatory Elements and Protein- ...

https://www.ecampus.com/biochemistry-short-course-4th-tymoczko/bk/9781319114633

The T7 RNA polymerase gene is cloned into the chromosomal lac operon. Since expression is controlled by the wt lac operon, ... When glycerol is the primary carbon source, there should no effect on the lac operon. ...

https://www.neb.com/faqs/2018/10/11/is-t7-expression-subject-to-catabolite-repression-in-neb-t7-express-or-shuffle-strains

Applications of optical communication: Bridging the lac operon The lac operon is one of the first genetic regulatory systems ... The purpose of the lac operon is that it encodes the genes that allow bacteria to break down lactose. In the absence of lactose ... this system enables us to optically bridge a physically separated canonical lac operon using light as a trans-acting factor, ... However, with the techniques of synthetic biology we can do something very interesting with the operon: we can separate the de- ...

https://2009.igem.org/wiki/index.php?title=Team:Harvard&oldid=161430

0: Lac operon (or other piece of cake) + our biobrick * 1: Less than 5 genes or biobricks (copy-paste) + our biobrick ...

https://2010.igem.org/wiki/index.php?title=Team:TU_Delft/Brainstorming&diff=prev&oldid=3819

Therefore, we dont need any fancy MacConkey agar combined with a lac operon. Yay! ...

https://2008.igem.org/Purdue/10_July_2008

Gene Action - Operon Hypothesis. Learn how the way genes control and determine every aspect of the body. This lesson uses lac ...

https://www.biologyonline.com/dictionary/hemizygous-gene

2021) Historical contingency causes divergence in adaptive expression of the lac operon Molecular Biology and Evolution 38:2869 ...

https://elifesciences.org/articles/76491

Lac Operon Medicine & Life Sciences 37% * Telencephalon Medicine & Life Sciences 37% View full fingerprint ...

https://moh-it.pure.elsevier.com/en/publications/epilepsy-and-brain-abnormalities-in-mice-lacking-the-otx1-gene

Zander, D.; Samaga, D.; Straube, R.; Bettenbrock, K.: Bistability and Nonmonotonic Induction of the lac Operon in the Natural ...

https://www.mpi-magdeburg.mpg.de/publication-search/1413561?person=%2Fpersons%2Fresource%2Fpersons96186

A preliminary test has shown correct reconstruction of lac operon model parameters derived from simulated expression data ...

https://www.iscb.org/cms_addon/conferences/ismb2003/posters/geneticsATsigex.com.br_283.html

Which of the following is not part of the lac operon?. A.. I. ... constitutive trp operon expression. B.. inducible trp operon ...

https://www.indiabix.com/biochemistry/genetic-regulation-prokaryotes/

Lac Operon (2) (Tagged with: Mountains of Creativity, student - Videos in this list also tagged with: Mountains of Creativity) ... Lac Operon (1) (Tagged with: Mountains of Creativity, student - Videos in this list also tagged with: Mountains of Creativity) ...

https://www.nextvista.org/tag/student/

Behe offered an overhead projection that covered terms ranging from "lac operon" and "galactosidase," to "repressor" and " ...

https://www.edweek.org/teaching-learning/defense-makes-its-case-in-intelligent-design-trial/2005/10

... reporter mouse model that combines a luciferase reporter gene under the control of regulatory elements from the lac operon of ... "Introduction of siRNA targeting lac repressor results in increased luciferase expression in cells where siRNA is biologically ... "Five founder luciferase-expressing and three founder Lac-expressing lines were generated and characterized," they noted. " ... "Mating of ubiquitously expressing luciferase and lac lines generated progeny in which luciferase expression was significantly ...

https://www.genomeweb.com/rnai/tools-techniques-screening-sirna-delivery-nanoparticles-reporter-model-sirna-pd

... with X-Gal or Bluo-Gal in blue-white selection of recombinant bacterial colonies that induce expression of the lac operon in ...

https://www.sigmaaldrich.com/MX/en/product/sigma/phg0010

Promoter (Pribnow box, TATA box) - Operon (Lac operon, Trp operon) - Terminator Enhancer - Repressor (Lac repressor, Trp ...

https://www.bionity.com/en/encyclopedia/Enhancer_%28genetics%29.html

The classic example is binding of lac repressor to two operator sites upstream of the promoter for the lac operon (Krämer et al ... Krämer, H., Niemöller, M., Amouyal, M., Revet, B., von Wilcken-Bergmann, B. and Müller-Hill, B. (1987) lac repressor forms ... DNA supercoiling changes the spacing requirement of two lac operators for DNA loop formation with lac repressor. The EMBO ... loops with linear DNA carrying two suitably spaced lac operators. The EMBO journal 6:1481-1491. [PDF]. Krämer, H., Amouyal, M ...

https://sandwalk.blogspot.com/2014/06/the-function-wars-part-i.html?showComment=1404177251696

Lac Operon 100% * Nervous System 10% * Neurons 48% * Olfactory Bulb 15% * P-Type Calcium Channels 21% ...

https://kyushu-u.pure.elsevier.com/en/publications/neuron-specific-expression-of-reporter-gene-in-transgenic-mice-ca/fingerprints/?sortBy=alphabetically

C23.888.592.612.451 Lac Operon G5.360.340.300.500.545 G5.360.340.358.207.500.545 Laryngismus C8.360.480 C8.360.895.500 C8.618. ... D27.505.259.750.600.825 rRNA Operon G5.360.340.300.500.817 G5.360.340.358.207.500.817 Russia Z1.252.122.500 Safrole J2.500. ... G5.360.340.358.207.500.645 Operon G5.360.340.300.500 G5.360.340.358.207.500 Ophthalmic Solutions D27.505.954.578.645 Opioid- ...

https://decs.bvs.br/P/mnchg2014.txt

The lac-operon is a group of genes involved in lactose metabolism. (biologycorner.com)
Students examine a graphic that shows the three genes associated with the operon. (biologycorner.com)
abstract = "This paper demonstrates that it is possible to use genetic programming to automatically create (reverse engineer) a computer program representing the logic underlying the genetic network for the expression level of the lac operon (composed of the Z, Y, and A genes) as measured by its mRNA. (upenn.edu)
I would appreciate it someone could explain clearly how the genes in the lac operon of E coli are activated to allow the bacteria to metabolize lactose? (dualjuridik.org)
The lac operon in E coli is a set of four genes which work together to allow the bacterium to make use of lactose for energy. (dualjuridik.org)
An Operon is a set of genes which are co-transcribed on a single mRNA, controlled from a common promoter. (dualjuridik.org)
While operons are nearly always found in bacteria, eukaryotes (and viruses that infect eukaryotes) do have some sets of genes organized into operons. (dualjuridik.org)
LacI binds to allolactose, a derivative of lactose, when it is present in sufficient quantities, which then causes it to release itself from the chromosomal DNA, allowing transcription to occur and the lac genes may be expressed. (dualjuridik.org)
In E. coli, and many other bacteria, genes encoding several different proteins may be located on a single transcription unit called an operon . (dualjuridik.org)
The genes in an operon share the same transcriptional regulation, but are translated individually. (dualjuridik.org)
Eukaryotes generally do not group genes together as operons (exception is C. elegans and a few other species). (dualjuridik.org)
For example, the bacterium Escherichia coli contains a number of genes clustered into operons and regulons: the Lac operon which is involved in lactose degradation, the Trp operon which is involved in tryptophan biosynthesis, and the His operon which is involved in histidine biosynthesis. (dualjuridik.org)
Control the expression of structural genes (code for enzymes of the same metabolic pathway) Repressor protein is active when its translated, will be inactivated when bound to lac. (oneclass.com)
If nonsense mutation occurs in all of the three genes, then no lac enzymes will be formed. (bartleby.com)
The purpose of the lac operon is that it encodes the genes that allow bacteria to break down lactose. (igem.org)
In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter . (explained.today)
The result of this is that the genes contained in the operon are either expressed together or not at all. (explained.today)
Several genes must be co-transcribed to define an operon. (explained.today)
This theory suggested that in all cases, genes within an operon are negatively controlled by a repressor acting at a single operator located before the first gene. (explained.today)
Today, the operon is simply defined as a cluster of genes transcribed into a single mRNA molecule. (explained.today)
rRNA genes often exist in operons that have been found in a range of eukaryotes including chordate s. (explained.today)
whereas operons contain a set of genes regulated by the same operator, regulons contain a set of genes under regulation by a single regulatory protein, and stimulons contain a set of genes under regulation by a single cell stimulus. (explained.today)
What is the function of the repressor gene, operator sequence, promoter, structural genes in the lac operon? (freezingblue.com)
What do the structural genes of the lac operon code for? (freezingblue.com)
How does the CAP regulation system affect expression of the lac operon structural genes? (freezingblue.com)
El gen regulador controla la síntesis de los tres genes estructurales: BETA GALACTOSIDASA, beta galactósido permeasa (implicada en el metabolismo de la lactosa) y beta tiogalactósido acetiltransferasa. (bvsalud.org)

The lac operon is one of the first genetic regulatory systems introduced to students of molecular biology: it is the poster-child for complex gene regulation in prokaryotes. (igem.org)

Lactose binds to the repressor and removes it from the promoter region of the operon. (biologycorner.com)
An operon is made up of several structural gene s arranged under a common promoter and regulated by a common operator. (explained.today)
All the structural gene s of an operon are turned ON or OFF together, due to a single promoter and operator upstream to them, but sometimes more control over the gene expression is needed. (explained.today)

The T7 RNA polymerase gene is cloned into the chromosomal lac operon. (neb.com)
The first operon codes for various products, including a special T7 RNA polymerase which can bind to and transcribe the second operon. (explained.today)

The lac-operon is an inducible operon. (biologycorner.com)
An inducible operon is one that is usually off. (dualjuridik.org)

lacI is a repressor gene - when it is active, it prevents the lac operon from being transcribed into RNA. (dualjuridik.org)
What is the function of the repressor gene in the lac operon? (freezingblue.com)

As such, the research group developed a positive-readout pharmacodynamic transgenic reporter mouse model that combines a luciferase reporter gene under the control of regulatory elements from the lac operon of Escherichia coli to allow noninvasive real-time assessment of siRNA activity. (genomeweb.com)

And the lac stands for the word lactose and the lac operon is found in the bacteria e. coli so it's a prokaryotic cell. (khanacademy.org)

If nonsense mutation takes place in the lac y, lac z or lac a gene , the mRNA of the gene in which the mutation has occured, will not be translated into enzyme and hence, no protein will be produced. (bartleby.com)
An operon contains one or more structural gene s which are generally transcribed into one polycistronic mRNA (a single mRNA molecule that codes for more than one protein ). (explained.today)
However, the definition of an operon does not require the mRNA to be polycistronic, though in practice, it usually is. (explained.today)

Practice: The protein that binds to the operator of the lac operon to prevent transcription is encoded by which gene? (clutchprep.com)
the lac operon was one of the first examples of transcription regulation every studied. (dualjuridik.org)

lacI is translated to the lac repressor protein (LacI), which binds to one of three sites in front of the lac operon. (dualjuridik.org)
Animate to switch from the apo form (dark colors) to the Trp-liganded form (medium colors) to the DNA-complex form (light colors) which binds both Trp and the operon DNA (the 3 forms were superimposed using the lower halves of the structures). (wustl.edu)

Since expression is controlled by the wt lac operon, glucose addition will result in catabolite repression. (neb.com)

In this case, the operon is repressible . (biologycorner.com)
Negative control involves turning off the operon in the presence of a repressor this can be either repressible or inducible. (dualjuridik.org)
A repressible operon is one that is usually on but which can be repressed in the presence of a repressor molecule. (dualjuridik.org)
Repressible operons are generally involved in anabolic pathways, or the synthesis of an essential component, while inducible operons are generally involved in catabolic pathways, or the breakdown of a nutrient. (dualjuridik.org)

lacZ and lacY is the business end of the lac operon. (dualjuridik.org)

The bacteria signal to yeast that the operon has been de-repressed using bioluminescence from the luciferase enzyme. (igem.org)
In these experiments, we have designed a system where bacteria signal to yeast that the operon has been de-repressed using bioluminescence from the luciferase enzyme. (igem.org)
Originally, operons were thought to exist solely in prokaryote s (which includes organelle s like plastid s that are derived from bacteria ), but since the discovery of the first operons in eukaryotes in the early 1990s, [3] [4] more evidence has arisen to suggest they are more common than previously assumed. (explained.today)

The 1965 Nobel Prize in Physiology and Medicine was awarded to François Jacob , André Michel Lwoff and Jacques Monod for their discoveries concerning the operon and virus synthesis. (explained.today)

An operon is a complete package for gene expression and synthesis of polypeptides. (dualjuridik.org)

Operons occur primarily in prokaryote s but also in some eukaryotes, including nematodes such as C. elegans and the fruit fly, Drosophila melanogaster . (explained.today)

This is an excellent demonstration of the principles and potential of synthetic biology: this system enables us to optically bridge a physically separated canonical lac operon using light as a trans-acting factor, communicated between the species of cells using optical signals. (igem.org)
However, with the techniques of synthetic biology we can do something very interesting with the operon: we can separate the de-repression and gene expression into two separate cells, bridging this physical separation with light based signals between the cells. (igem.org)

Thus, this explains that operon acts as a unit of genetic expression. (bartleby.com)
A preliminary test has shown correct reconstruction of lac operon model parameters derived from simulated expression data collected following a perturbation in the level of lactose. (iscb.org)
Introduction of siRNA targeting lac repressor results in increased luciferase expression in cells where siRNA is biologically active," they wrote in Molecular Therapy - Nucleic Acids . (genomeweb.com)
Mating of ubiquitously expressing luciferase and lac lines generated progeny in which luciferase expression was significantly reduced compared with the parental line. (genomeweb.com)
Intraperitoneal administration of siRNA targeting lac in combination with a lipid transfection reagent increased luciferase expression in the liver, while control siRNAs had no effect, according to the team. (genomeweb.com)
[5] In general, expression of prokaryotic operons leads to the generation of polycistronic mRNAs, while eukaryotic operons lead to monocistronic mRNAs. (explained.today)

What is the significance of and biological mechanisms demonstrated in lac operon? (dualjuridik.org)
Therefore, it is not possible to talk of a general regulatory mechanism, because different operons have different mechanisms. (explained.today)

This lesson uses lac operon as an example. (biologyonline.com)

5 [10] The regulators of a given operon, including repressor s, corepressor s, and activator s, are not necessarily coded for by that operon. (explained.today)

Five founder luciferase-expressing and three founder Lac-expressing lines were generated and characterized," they noted. (genomeweb.com)

The recombinants are conveniently detected as white colonies by the familiar blue/white screening test for lac Z activity. (biomedcentral.com)

Binding of lactose to lac repressor is transient, Repressor now able to bind to operator. (oneclass.com)

Operons are also found in viruses such as bacteriophage s. [6] [7] For example, T7 phage s have two operons. (explained.today)

Which enzyme will be produced in a cell where a nonsense mutation is present in the lac operon? (bartleby.com)
The second operon includes a lysis gene meant to cause the host cell to burst. (explained.today)
What is the major function of the lac operon in cell metabolism? (freezingblue.com)

If the nonsense mutation takes place at the operator , then simultaneous constitutivity for all the products of the operon will take place. (bartleby.com)

Bistability and Nonmonotonic Induction of the lac Operon in the Natural Lactose Uptake System. (mpg.de)

These operons are turned on when the gene products are needed. (dualjuridik.org)

The term "operon" was first proposed in a short paper in the Proceedings of the French Academy of Science in 1960. (explained.today)

Operons can be under negative or positive control. (dualjuridik.org)

Anatomy1

Organisms8

Chemicals and Drugs32

Analytical, Diagnostic and Therapeutic Techniques and Equipment12

Phenomena and Processes39

Disciplines and Occupations2

Information Science4

Health Care1

Transcriptional repression by the Drosophila giant protein: cis element positioning provides an alternative means of interpreting an effector gradient. (1/2991)

Accelerated accumulation of somatic mutations in mice deficient in the nucleotide excision repair gene XPA. (2/2991)

Adenoviral gene transfer into the normal and injured spinal cord: enhanced transgene stability by combined administration of temperature-sensitive virus and transient immune blockade. (3/2991)

Transduction of glioma cells using a high-titer retroviral vector system and their subsequent migration in brain tumors. (4/2991)

Murine matrix metalloproteinase 9 gene. 5'-upstream region contains cis-acting elements for expression in osteoclasts and migrating keratinocytes in transgenic mice. (5/2991)

Reduced differentiation potential of primary MyoD-/- myogenic cells derived from adult skeletal muscle. (6/2991)

Efflux-mediated aminoglycoside and macrolide resistance in Burkholderia pseudomallei. (7/2991)

Aging-specific expression of Drosophila hsp22. (8/2991)

Lac Operon

Operon

Lactose

Lac Repressors

Galactosidases

Escherichia coli

Isopropyl Thiogalactoside

beta-Galactosidase

Enzyme Repression

Gene Expression Regulation, Bacterial

Genes, Bacterial

Nitrophenylgalactosides

Bacterial Proteins

Molecular Biology

Base Sequence

Escherichia coli Proteins

DNA, Bacterial

rRNA Operon

Genes, Regulator

Mutation

Transcription, Genetic

Molecular Sequence Data

Cyclic AMP Receptor Protein

Operator Regions, Genetic

Thiogalactosides

Repressor Proteins

RNA, Bacterial

Genetics, Microbial

Chromosomes, Bacterial

Bacteriophage mu

Promoter Regions, Genetic

Cloning, Molecular

Salmonella typhimurium

Galactose

Genes

Plasmids

Enzyme Induction

Membrane Transport Proteins

Transduction, Genetic

Coliphages

Genetic Code

Glycosides

DNA Transposable Elements

DNA, Recombinant

Chromosome Mapping

DNA-Directed RNA Polymerases

Amino Acid Sequence

Models, Genetic

Nucleic Acid Conformation

Bacillus subtilis

Stochastic Processes

Glucose

RNA, Messenger

Culture Media

Species Specificity

Restriction Mapping

Lactose Factors

Genetic Complementation Test

Recombination, Genetic

Cyclic AMP

Gene Expression Regulation

Mutagenesis, Insertional

Phenotype

Kinetics

Sequence Analysis, DNA

Arabinose

Transcription Factors

Kluyveromyces

Multigene Family

DNA Restriction Enzymes

Regulon

Open Reading Frames

Conjugation, Genetic

Sequence Homology, Nucleic Acid

Genome, Bacterial

Laccase

Models, Biological

Sequence Homology, Amino Acid

Sigma Factor

Terminator Regions, Genetic