In order to study the evolution of the chromosomal beta-lactamase gene in K. pneumoniae, we analyzed the diversity of the gene in strains representing the known range of K. pneumoniae genetic diversity. This approach revealed a close correspondence between the chromosomal beta-lactamase gene sequences and the previously defined phylogenetic groups of K. pneumoniae. It also made it possible to identify a new family of beta-lactamase variants.. Phylogenetic analyses of the bla, gyrA, and mdh sequences were all in agreement, showing three major groups. Our results firmly demonstrated the correspondence between the phylogenetic group KpI and the SHV family, as well as between group KpIII and the LEN family. Also, the pI values of the beta-lactamases paralleled the grouping; thus, pI 7.6 (SHV-like) was seen for all KpI strains and pI 7.1 (LEN-like) was seen for all KpIII strains.. Strain SB30 and strain OR95:2, a strain previously shown to harbor a chromosomal beta-lactamase gene different from both ...
Dimer formation is a serious threat to the stable maintenance of ColE1-like plasmids. Dimers form infrequently by homologous recombination but accumulate rapidly by having two origins of replication. This results in elevated plasmid loss and a reduction in host cell growth rate. Plasmid dimers are resolved to monomers by the XerCD recombinase plus accessory proteins ArgR and PepA, acting at the cer recombination site. The circular chromosome of E. coli also forms dimers infrequently, and consequent failure of chromosome partition results in filamentation, SOS induction, and failure of cell division. Site-specific recombination is required for dimer resolution during cell division in a process facilitated by XerCD acting at the dif (deletion induced filamentation) site near the E. coli chromosome terminus. ArgR and PepA accessory proteins are nonessential, but the septum-associated protein FtsK is necessary for dimer segregation, suggesting the XerCD/difcomplex interacts with division septums. Our
McCool JD, Sandler SJ. 2001. Effects of mutations involving cell division, recombination, and chromosome dimer resolution on a priA2::kan mutant.. Proc Natl Acad Sci U S A. 98(15):8203-10. ...
In a eukaryotic cell, chromosome replication occurs during DNA synthesis, or the S phase of the cell cycle. In its normal state, a chromosome is a long, thin chromatin fiber containing one DNA...
Binary fission can refer to cell division in bacteria. Bacteria replicate their chromosomes prior to division, but I dont think that state can be called diploid because the chromosomes are identical. Diploid organisms can be carrying different alleles on each pair of sister chromosomes, but this is not the case for a duplicated bacterial chromosome before cell division. Therefore in my opinion your statement is not necessarily true, at least for bacteria ...
We are investigating the structure of E. coli chromosome and the pathway of its compaction to the nucleoid state by taking several approaches: (i) by genetically analyzing mutant cells defective in the nucleoid protein HU; (ii) by studying nuclease
We have identified a DNA site involved in chromosome partitioning in B. subtilis. This site was identified in vivo as the binding site for the chromosome partitioning protein Spo0J, a member of the ParB family of partitioning proteins. Spo0J is a site-specific DNA-binding protein that recognizes a 1 …
DNA Biological Functions In eukaryotes, the DNA occurs as linear chromosomes. And in prokaryotes the DNA occurs as circular chromosomes.
Studies of chromosome organization in bacterial cells show that the chromosome is an exquisitely organized and dynamic structure (reviewed recently in Thanbichler et al., 2005). Chromosome segregation in bacteria does not occur all at once but in sequential phases (Lau et al., 2003; Viollier et al., 2004; Bates and Kleckner, 2005; Nielsen et al., 2006). After replication at mid-cell, the origin region (oriC) is rapidly segregated outward. The speed at which this occurs (reviewed in Gordon and Wright, 2000) rules out passive models for bacterial chromosome segregation, which proposed that outward cellular growth could drive the movement of a fixed chromosome. As the loci of the chromosome are replicated, they are moved outward to the poles in a sequential fashion (Lau et al., 2003; Viollier et al., 2004; Bates and Kleckner, 2005; Nielsen et al., 2006). In Escherichia coli, there may be a period of sister chromosome cohesion between duplication and subsequent segregation, although its length is ...
The complete genome of Vibrio cholerae El Tor N16961 consists of two circular chromosomes (2,961,146 and 1,072,313 base pair) with 3,890 predicted open reading frames (2,775 and 1,115 on each chromosome respectively). The majority of recognizable genes for essential cell functions (such as DNA replication, transcription, translation, etc.) and pathogenicity (such as toxin, surface antigens, and adhesion) are located on the large chromosome. The small chromosome contains a large percentage of hypothetical genes, more genes that appear to have origins other than the Proteobacteria, a gene capture system (integron island) that suggests this may have been a mega-plasmid captured by an ancestral Vibrio species. The Vibrio cholerae genome sequence provides a starting point for understanding how a free living, environmental microorganism is also a human pathogen. Source: The Institute for Genomic Research ...
Sequencing of the complete Bacillus subtilis chromosome revealed the presence of approximately 4100 genes, 1000 of which were previously identified and mapped by classical genetic crosses. Comparison of these experimentally determined positions to th
Our suspicion that the V. cholerae chromosome may exist as two separate replicons was based on the observation that when undigested genomic DNA was subjected to electrophoresis, two megabase-sized fragments were visible. In addition, we were unable to convincingly link the I-CeuI fragments into a single circular chromosome. The final clue came from the observation that immobilized genomic DNA subjected to pulsed-field gel electrophoresis after digestion with another rarely cutting restriction enzyme, I-SceI, produced two fragments, the smaller of which appeared exactly like one of two megabase-sized fragments produced by I-CeuI digestion. This fragment in both digestions always appeared to stain lighter than the other bands. We now have confirmed (by linkage of SfiI fragments contained in this band) that this fragment was not cut by either I-SceI or I-CeuI; the presumed reason it did not stain well was because it was constrained in its uptake of ethidium bromide by its covalently closed circular ...
WT cells under nutrient limitation exhibit two distinct regimes according to the Helmstetter-Cooper (HC) model of bacterial chromosome replication (Appendix Fig S9): In the fast growth regime (doubling time DT , single‐chromosome replication time, the "C‐period"), the C‐period is constant (at its minimal value) and the total DNA synthesis rate is determined by the replication initiation rate. In the slow growth regime (DT , C‐period), chromosome replication is limited by the replication fork elongation rate, which is in turn limited by the synthesis of nucleotides (DNA monomers) (Neidhart, 1996). Under LacZ OE, the DNA content increases (Figs 1F and EV3A and B). Since multiple chromosome equivalents per cell are observed in a single nucleoid complex (Fig EV3), the HC model of DNA replication may still be applicable with multiple replication forks per cell, provided that the C‐period , DT. The increase in DT under LacZ OE then implies that the C‐period would have to increase at least ...
View DNA Rearrangements from BIOLOGY MCB2010 at Broward College. Examples : Integration of bacteriophage DNA into host bacterial chromosome Immunoglobulin and T Cell Receptor genes DNA rearrangements
Strain MK423 was grown under the same conditions as used when growing cells for microscopy analysis; cells of OD600 = 0.4 were diluted 100-fold in C+Y medium with 0.1 mM ZnCl2 and incubated for 2.5 hours until OD600 = 0.15. Cells were then harvested by centrifugation for 5 min at 6500 x g at 4°C. Genomic DNA was isolated using the Wizard® Genomic DNA Purification Kit (Promega) as described previously (Slager et al. 2014 Cell). Fragmentation was performed using Covaris instrument, and libraries ...
View Notes - Chapter 9 from BIO SCI 325 at Wisconsin Milwaukee. 1 204-325 2 h h Chromosomal mutations are variations from Chromosomal mutations are variations from wild wild-- type condition in
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InterPro provides functional analysis of proteins by classifying them into families and predicting domains and important sites. We combine protein signatures from a number of member databases into a single searchable resource, capitalising on their individual strengths to produce a powerful integrated database and diagnostic tool.
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This model represents a family of conserved hypothetical proteins. It is usually (but not always) found in apparent phage-derived regions of bacterial chromosomes ...
In budding yeast replication origins, the 11-bp ARS consensus sequence is essential for interaction with the ORC. However, replication origins in other eukaryotic species, including fission yeast, do not appear to contain a short essential sequence (15,23) and it has not been known whether the ORC is located at chromosomal replication origins. The present study demonstrated that a fission yeast ORC subunit and an Mcm protein are specifically localized at chromosomal replication origins. Orp1p is located at thears2004 and ars3002 loci throughout the cell cycle, while SpMcm6p is associated with these origins only in the G1 and S phases. To our knowledge, this is the first indication of preferential localization of the ORC and Mcm proteins at the chromosomal replication origins in eukaryotic species except for budding yeast.. The CHIP assay finding that Orp1p was localized at ars2004and ars3002 but not at non-ARS regions (Fig. 6) suggests that a certain sequence or DNA structure in the replication ...
The study of chromosomal replication and cell division of bacteria has extended beyond Escherichia coli, and important insights have emerged recently from studies in other species, especially Bacillus subtilis and Caulobacter crescentus. Cell division is coordinated with other cell cycle events such as genomic DNA synthesis that leads to chromosomal replication and partition, increase of cell mass, and cell expansion by cell wall synthesis. This chapter reviews the information about predicted genes related to chromosomal replication, plasmid replication, and cell division in Helicobacter pylori, and a plausible replication machinery of the bacterium is discussed in light of the current understanding of bacterial organization and function of replication and cell division. The DnaA protein is essential for the initiation of chromosomal replication and is highly conserved among different bacteria. Clinical isolates of H. pylori have been reported to carry plasmids ranging in size from 1.5 to 40 kb. Three
Bacteria with multiple chromosomes represent up to 10% of all bacterial species. Unlike eukaryotes, these bacteria use chromosome-specific initiators for their replication. In all cases investigated, the machineries for secondary chromosome replication initiation are of plasmid origin. One of the important differences between plasmids and chromosomes is that the latter replicate during a defined period of the cell cycle, ensuring a single round of replication per cell. Vibrio cholerae carries two circular chromosomes, Chr1 and Chr2, which are replicated in a well-orchestrated manner with the cell cycle and coordinated in such a way that replication termination occurs at the same time. However, the mechanism coordinating this synchrony remains speculative. We investigated this mechanism and revealed that initiation of Chr2 replication is triggered by the replication of a 150-bp locus positioned on Chr1, called crtS. This crtS replication-mediated Chr2 replication initiation mechanism explains how ...
Structural elements of the Streptomyces oriC region and their interactions with the DnaA protein. Transcription analysis of the dnaA gene and oriC region of the chromosome of Mycobacterium smegmatis and Mycobacterium bovis BCG, and its regulation by the DnaA protein
In Escherichia coli, chromosome replication is initiated from oriC by the DnaA initiator protein associated with ATP. Three non-coding regions contribute to the activity of DnaA. The datA locus is instrumental in conversion of DnaAATP to DnaAADP (DDAH; datA dependent DnaAATP hydrolysis) whereas DnaA rejuvenation sequences 1 and 2 (DARS1 and DARS2) reactivate DnaAADP to DnaAATP. The structural organization of oriC, datA, DARS1 and DARS2 were found conserved between 59 fully sequenced E. coli genomes, with differences primarily in the non-functional spacer regions between key protein binding sites. The relative distances from oriC to datA, DARS1 and DARS2, respectively, was also conserved despite of large variations in genome size, suggesting that the gene dosage of either region is important for bacterial growth. Yet all three regions could be deleted alone or in combination without loss of viability. Competition experiments during balanced growth in rich medium and during mouse colonization indicated
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This Lesson 8: Mitosis: Chromosome Replication & Division Lesson Plan is suitable for 9th - 12th Grade. Students complete the Mitosis exercise net which contains the basic concepts and relations to describe mitosis.
Synopses of papers: The 187th Meeting of the Pathological Society of Great Britain and Ireland, The Robin Brook Centre, St. Bartholomews Hospital, London, 6-7 January 2005 ...
Two global genome features based on OU statistics were considered in this study: PS and OUV. They provide non-redundant characteristics of the complete sequence of genomes and allow the discrimination of bacterial, plasmid and phage genomes by phylogeny, the arrangement of coding and non-coding sequence and the distribution of islands and islets.. A strong taxonomic signal was observed in genome specific OUV values. Strains belonging to the same species or genus usually have similar OUV. In general, the higher is the OUV, the less random is the sequence. Multiple influences such as DNA structure and topology, codon usage, DNA repair and restriction-modification systems contribute to the surrogate parameter OUV, and hence it is plausible that the OUV is a taxon-specific feature. Future work on the frequency and distribution of individual words should elucidate the biological meaning of the genome specific OUV for the individual taxon (see Weinel et al., 2002 [40] as one of the few published ...
These researchers are studying spatial patterns of transcriptional activity in the chromosome of Escherichia coli. Genes on the bacterial chromosome, as well as on any other chromosome of any organism, are arranged in a certain linear order. How this order contributes to transcriptional regulation of groups of genes is the main focus of this research. ...
Scientists at the J. Craig Venter Institute (JCVI), a genomics research facility, transplanted a bacterial chromosome from one type of bacteria into anothe
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When DNA gyrase is trapped on bacterial chromosomes by quinolone antibacterials, reversible complexes form that contain DNA ends constrained by protein. Two subsequent processes lead to rapid cell death. One requires ongoing protein synthesis; the other does not. The prototype quinolone, nalidixic acid, kills wild-type Escherichia coli only by the first pathway; fluoroquinolones kill by both. Both lethal processes correlated with irreversible chromosome fragmentation, detected by sedimentation and viscosity of DNA from quinolone-treated cells. However, only fluoroquinolones fragmented purified nucleoids when incubated with gyrase purified from wild-type cells. A GyrA amino acid substitution (A67S) expected to perturb a GyrA-GyrA dimer interface allowed nalidixic acid to fragment chromosomes and kill cells in the absence of protein synthesis; moreover, it made a non-inducible lexA mutant hypersusceptible to nalidixic acid, a property restricted to fluoroquinolones with wild-type cells. The GyrA variation
The Escherichia coli DnaA protein is a sequence-specific DNA binding protein that promotes the initiation of replication of the bacterial chromosome, and of several plasmids including pSC101. Twenty-eight novel missense mutations of the E. coli dnaA gene were isolated by selecting for their inabilit …
The structural maintenance of chromosomes (SMC) complex plays an important role in chromosome organization and segregation in most living organisms. In Caulobacter crescentus, SMC is required to align the left and the right arms of the chromosome that run in parallel down the long axis of the cell. However, the mechanism of SMC-mediated alignment of chromosomal arms remains elusive. Here, using genome-wide methods and microscopy of single cells, we show that Caulobacter SMC is recruited to the centromeric parS site and that SMC-mediated arm alignment depends on the chromosome-partitioning protein ParB. We provide evidence that SMC likely tethers the parS-proximal regions of the chromosomal arms together, promoting arm alignment. Furthermore, we show that highly transcribed genes near parS that are oriented against SMC translocation disrupt arm alignment, suggesting that head-on transcription interferes with SMC translocation. Our results demonstrate a tight interdependence of bacterial chromosome
... teaches people how to trace their bloodlines through chromosome mapping to confirm ancestors. Chromosome mapping collaboration can help confirm the presence of dna signatures on chromosomes left by ordinary, famous or noble ancestors. Chromosome mapping can help trace ancient bloodlines by using end location numbers of CM on chromosomes. Members get access to the database to add information of bloodlines they have mapped and to find end location numbers of researched ancestors and famous people.
Chromosomal mutations occur inside the chromosome. There are 23 pairs of chromosomes in each human cell. Mutation occurs in the genes DNA base sequence. There are several factors associated with gene mutation. Some mutations are hereditary while others occur due to environmental factors in an individuals lifetime. Learn more facts about chromosomal mutations.
He J, Mao C-C, Reyes A, Sembongi H, Di Re M, Granycome C, Clippingdale AB, Fearnley IM, Harbour M, Robinson AJ, Reichelt S, Spelbrink JN, Walker JE & Holt IJ (2007) The AAA+ protein ATAD3 has displacement loop binding properties and is involved in mitochondrial nucleoid organization. J Cell Biol 176, 141-6 ...
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During a 3-year period, 848 patients were detected as carriers of methicillin-resistant Staphylococcus aureus (MRSA) by the Xpert MRSA assay (Cepheid). Among them, 108 patients (12.7 %) were colonized with strains showing methicillin-susceptible phenotypes and absence of the mecA gene, despite being positive with the rapid polymerase chain reaction (PCR) assay. DNA sequences of the staphylococcal cassette chromosome mec (SCCmec) insertion site of these false-positive strains was determined by direct sequencing of the genomic DNA. More than half (53.7 %) of the strains had DNA sequences unrelated to either SCC or SCCmec and one-third had DNA sequences related to non-mec SCC. Only 10.2 % of the strains carried sequences related to SCCmec, suggesting that a sequence containing the mecA gene was lost from an SCCmec. These findings differ from the general idea that all methicillin-susceptible S. aureus having positive Xpert MRSA assay results are essentially MRSA that lost the mecA gene.
METHODS:. A total of 19 S. hominis isolates were collected from children at the Childrens Medical Centre, Tehran, Iran, from March 2012 to February 2013. MRSHo susceptibility against 13 antimicrobial and 3 antiseptic agents was determined using disk diffusion (DAD) and minimum inhibitory concentration (MIC), respectively. All isolates were subjected to polymerase chain reaction (PCR) assay for 15 distinct resistance genes, staphylococcal cassette chromosome mec (SCCmec), and arginine catabolic mobile elements (ACMEs). Biofilm production of the isolates was determined using a colorimetric microtiter plate assay. ...
To determine the predominant staphylococcal cassette chromosome (SCC) mec element in methicillin-resistant Staphylococcus aureus, we typed 190 isolates from a hospital in Taiwan. We found a shift from type IV to type III SCCmec element during 1992-2003, perhaps caused by selective pressure from indiscriminate use of antimicrobial drugs.
To determine the predominant staphylococcal cassette chromosome (SCC) mec element in methicillin-resistant Staphylococcus aureus, we typed 190 isolates from a hospital in Taiwan. We found a shift from type IV to type III SCCmec element during 1992-2003, perhaps caused by selective pressure from indiscriminate use of antimicrobial drugs.
Recent studies of mutations accumulated nonselectively across bacterial chromosomes revealed that rates of base-pair substitutions (BPSs) vary 2-fold to 4-fold in a wave-like pattern that is mirrored in the two independently replicating halves of the chromosome. These symmetrical patterns have been observed in mismatch repair (MMR)-defective strains of Escherichia coli (1), Vibrio fischeri, V. cholerae (2-4), Pseudomonas fluorescens (5), and P. aeruginosa (6). Such variations in mutation rates may affect the pace at which genes in different regions of the chromosome evolve and may exert selective pressure on gene placement. Yet the causes of this variation are not known.. The fidelity of DNA replication, which, in E. coli, is about 1 mistake in 1,000 generations (7), is determined by the intrinsic accuracy of the DNA polymerase plus error correction by proofreading and MMR (8, 9). In E. coli, proofreading is performed by epsilon, a subunit of the DNA polymerase III holoenzyme. If the polymerase ...
In bacterial genomes composed of more than one chromosome, one replicon is typically larger, harbors more essential genes than the others, and is considered primary. The greater variability of secondary chromosomes among related taxa has led to the theory that they serve as an accessory genome for specific niches or conditions. By this rationale, purifying selection should be weaker on genes on secondary chromosomes because of their reduced necessity or usage. To test this hypothesis we selected bacterial genomes composed of multiple chromosomes from two genera, Burkholderia and Vibrio, and quantified the evolutionary rates (dN and dS) of all orthologs within each genus. Both evolutionary rate parameters were faster among orthologs found on secondary chromosomes than those on the primary chromosome. Further, in every bacterial genome with multiple chromosomes that we studied, genes on secondary chromosomes exhibited significantly weaker codon usage bias than those on primary chromosomes. Faster
The Escherichia coli chromosome is organized into four macrodomains, the function and organisation of which are poorly understood. In this review we focus on the MatP, SeqA, and SlmA proteins that have recently been identified as the first examples of factors with macrodomain-specific DNA-binding properties. In particular, we review the evidence that these factors contribute towards the control of chromosome replication and segregation by specifically targeting subregions of the genome and contributing towards their unique properties. Genome sequence analysis of multiple related bacteria, including pathogenic species, reveals that macrodomain-specific distribution of SeqA, SlmA, and MatP is conserved, suggesting common principles of chromosome organisation in these organisms. This discovery of proteins with macrodomain-specific binding properties hints that there are other proteins with similar specificity yet to be unveiled. We discuss the roles of the proteins identified to date as well as ...
Author Summary Multi-drug resistant bacteria continue to emerge and there is a pressing need for the development of new antibiotics. Here, we carried out a cell-based high throughput screen to identify inhibitors of RctB, the initiator of replication of the second chromosome found in all the species of the Vibrionaceae. This family of bacteria includes several human pathogens, including Vibrio cholerae, the cause of cholera, as well as several species that damage economically important marine organisms. We identified a compound-designated vibrepin-that has potent cidal activity against V. cholerae and inhibited growth of all vibrio species tested. Vibrepin blocked RctB unwinding of the origin of replication of the second V. cholerae chromosome, apparently by promoting the formation of large non-functional RctB complexes. Vibrepin represents a new class of antibiotic that specifically targets a particular family of microorganisms (the Vibrionaceae). Such targeted agents will not engender resistance in
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Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring. Most recombination is naturally occurring. During meiosis in eukaryotes, genetic recombination involves the pairing of homologous chromosomes. This may be followed by information transfer between the chromosomes. The information transfer may occur without physical exchange (a section of genetic material is copied from one chromosome to another, without the donating chromosome being changed) (see SDSA pathway in Figure); or by the breaking and rejoining of DNA strands, which forms new molecules of DNA (see DHJ pathway in Figure). Recombination may also occur during mitosis in eukaryotes where it ordinarily involves the two sister chromosomes formed after chromosomal replication. In this case, new combinations of ...