Mycobacterium smegmatis: A rapid-growing, nonphotochromogenic species of MYCOBACTERIUM originally isolated from human smegma and found also in soil and water. (From Dorland, 28th ed)Mycobacterium: A genus of gram-positive, aerobic bacteria. Most species are free-living in soil and water, but the major habitat for some is the diseased tissue of warm-blooded hosts.Mycobacterium tuberculosis: A species of gram-positive, aerobic bacteria that produces TUBERCULOSIS in humans, other primates, CATTLE; DOGS; and some other animals which have contact with humans. Growth tends to be in serpentine, cordlike masses in which the bacilli show a parallel orientation.Mycobacterium bovis: The bovine variety of the tubercle bacillus. It is called also Mycobacterium tuberculosis var. bovis.Mycobacterium avium: A bacterium causing tuberculosis in domestic fowl and other birds. In pigs, it may cause localized and sometimes disseminated disease. The organism occurs occasionally in sheep and cattle. It should be distinguished from the M. avium complex, which infects primarily humans.Mycobacterium Infections: Infections with bacteria of the genus MYCOBACTERIUM.Nontuberculous Mycobacteria: So-called atypical species of the genus MYCOBACTERIUM that do not cause tuberculosis. They are also called tuberculoid bacilli, i.e.: M. buruli, M. chelonae, M. duvalii, M. flavescens, M. fortuitum, M. gilvum, M. gordonae, M. intracellulare (see MYCOBACTERIUM AVIUM COMPLEX;), M. kansasii, M. marinum, M. obuense, M. scrofulaceum, M. szulgai, M. terrae, M. ulcerans, M. xenopi.Mycobacteriophages: Viruses whose host is one or more Mycobacterium species. They include both temperate and virulent types.Mycobacterium Infections, Nontuberculous: Infections with nontuberculous mycobacteria (atypical mycobacteria): M. kansasii, M. marinum, M. scrofulaceum, M. flavescens, M. gordonae, M. obuense, M. gilvum, M. duvali, M. szulgai, M. intracellulare (see MYCOBACTERIUM AVIUM COMPLEX;), M. xenopi (littorale), M. ulcerans, M. buruli, M. terrae, M. fortuitum (minetti, giae), M. chelonae.Mycobacterium leprae: A species of gram-positive, aerobic bacteria that causes LEPROSY in man. Its organisms are generally arranged in clumps, rounded masses, or in groups of bacilli side by side.Bacterial Proteins: Proteins found in any species of bacterium.Mycobacterium fortuitum: A rapid-growing, nonphotochromogenic species that is potentially pathogenic, producing lesions of lung, bone, or soft tissue following trauma. It has been found in soil and in injection sites of humans, cattle, and cold-blooded animals. (Dorland, 28th ed)Mycolic AcidsMycobacterium avium Complex: A complex that includes several strains of M. avium. M. intracellulare is not easily distinguished from M. avium and therefore is included in the complex. These organisms are most frequently found in pulmonary secretions from persons with a tuberculous-like mycobacteriosis. Strains of this complex have also been associated with childhood lymphadenitis and AIDS; M. avium alone causes tuberculosis in a variety of birds and other animals, including pigs.Mycobacterium chelonae: A species of gram-positive, aerobic bacteria commonly found in soil and occasionally isolated from sputum. It causes postoperative wound infections as well as gluteal abscesses.Antitubercular Agents: Drugs used in the treatment of tuberculosis. They are divided into two main classes: "first-line" agents, those with the greatest efficacy and acceptable degrees of toxicity used successfully in the great majority of cases; and "second-line" drugs used in drug-resistant cases or those in which some other patient-related condition has compromised the effectiveness of primary therapy.Ethambutol: An antitubercular agent that inhibits the transfer of mycolic acids into the cell wall of the tubercle bacillus. It may also inhibit the synthesis of spermidine in mycobacteria. The action is usually bactericidal, and the drug can penetrate human cell membranes to exert its lethal effect. (From Smith and Reynard, Textbook of Pharmacology, 1992, p863)Mycobacterium phlei: A saprophytic bacterium widely distributed in soil and dust and on plants.Mycobacterium marinum: A moderate-growing, photochromogenic species found in aquariums, diseased fish, and swimming pools. It is the cause of cutaneous lesions and granulomas (swimming pool granuloma) in humans. (Dorland, 28th ed)Tuberculosis: Any of the infectious diseases of man and other animals caused by species of MYCOBACTERIUM.Mycobacterium kansasii: A slow-growing, photochromogenic species that is the etiologic agent of a tuberculosis-like disease in humans and is frequently isolated from human pulmonary secretions or tubercles. The incidence of infection is sharply increased among immunocompromised individuals. (Dorland, 28th ed)Molecular Sequence Data: 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.Mycobacterium avium subsp. paratuberculosis: A subspecies of gram-positive, aerobic bacteria. It is the etiologic agent of Johne's disease (PARATUBERCULOSIS), a chronic GASTROENTERITIS in RUMINANTS.Isoniazid: Antibacterial agent used primarily as a tuberculostatic. It remains the treatment of choice for tuberculosis.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Genes, Bacterial: The functional hereditary units of BACTERIA.Galactans: Polysaccharides composed of repeating galactose units. They can consist of branched or unbranched chains in any linkages.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Mycobacterium avium-intracellulare Infection: A nontuberculous infection when occurring in humans. It is characterized by pulmonary disease, lymphadenitis in children, and systemic disease in AIDS patients. Mycobacterium avium-intracellulare infection of birds and swine results in tuberculosis.Viomycin: A strongly basic peptide, antibiotic complex from several strains of Streptomyces. It is allergenic and toxic to kidneys and the labyrinth. Viomycin is used in tuberculosis as several different salts and in combination with other agents.Mycobacterium ulcerans: A slow-growing mycobacterium that infects the skin and subcutaneous tissues, giving rise to indolent BURULI ULCER.Cell Wall: The outermost layer of a cell in most PLANTS; BACTERIA; FUNGI; and ALGAE. The cell wall is usually a rigid structure that lies external to the CELL MEMBRANE, and provides a protective barrier against physical or chemical agents.Glycopeptides: Proteins which contain carbohydrate groups attached covalently to the polypeptide chain. The protein moiety is the predominant group with the carbohydrate making up only a small percentage of the total weight.Rifampin: A semisynthetic antibiotic produced from Streptomyces mediterranei. It has a broad antibacterial spectrum, including activity against several forms of Mycobacterium. In susceptible organisms it inhibits DNA-dependent RNA polymerase activity by forming a stable complex with the enzyme. It thus suppresses the initiation of RNA synthesis. Rifampin is bactericidal, and acts on both intracellular and extracellular organisms. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1160)Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Amino Acid Sequence: 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.Ergothioneine: A naturally occurring metabolite of HISTIDINE that has antioxidant properties.Microbial Sensitivity Tests: Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).Ethionamide: A second-line antitubercular agent that inhibits mycolic acid synthesis.Tuberculosis, Pulmonary: MYCOBACTERIUM infections of the lung.Glycolipids: Any compound containing one or more monosaccharide residues bound by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol (see GLYCERIDES), a sphingoid, a ceramide (CERAMIDES) (N-acylsphingoid) or a prenyl phosphate. (From IUPAC's webpage)Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Alanine Racemase: A pyridoxal-phosphate protein that reversibly catalyzes the conversion of L-alanine to D-alanine. EC An isomer of glucose that has traditionally been considered to be a B vitamin although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1379) Inositol phospholipids are important in signal transduction.Cord Factors: Toxic glycolipids composed of trehalose dimycolate derivatives. They are produced by MYCOBACTERIUM TUBERCULOSIS and other species of MYCOBACTERIUM. They induce cellular dysfunction in animals.Drug Resistance, Bacterial: The ability of bacteria to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Cycloserine: Antibiotic substance produced by Streptomyces garyphalus.Mutation: 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.Culture Media: 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.Polysorbates: Sorbitan mono-9-octadecanoate poly(oxy-1,2-ethanediyl) derivatives; complex mixtures of polyoxyethylene ethers used as emulsifiers or dispersing agents in pharmaceuticals.Microbial Viability: Ability of a microbe to survive under given conditions. This can also be related to a colony's ability to replicate.Genetic Complementation Test: 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.DNA Transposable Elements: 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.Capreomycin: Cyclic peptide antibiotic similar to VIOMYCIN. It is produced by Streptomyces capreolus.Rhamnose: A methylpentose whose L- isomer is found naturally in many plant glycosides and some gram-negative bacterial lipopolysaccharides.Drug Resistance, Microbial: The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Methylmannosides: Mannosides formed by the reaction of the hydroxyl group on the anomeric carbon atom of mannose with methyl alcohol. They include both alpha- and beta-methylmannosides.Cloning, Molecular: 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.Gene Deletion: 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.RNA, Bacterial: Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Streptomycin: An antibiotic produced by the soil actinomycete Streptomyces griseus. It acts by inhibiting the initiation and elongation processes during protein synthesis.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Tuberculosis Vaccines: Vaccines or candidate vaccines used to prevent or treat TUBERCULOSIS.Mycobacterium lepraemurium: The etiologic agent of rat leprosy, also known as murine leprosy.Mycobacterium scrofulaceum: A non-tuberculous mycobacterium causing cervical lymphadenitis in children. It very rarely causes pulmonary disease, and is believed to be non-pathogenic in animals.Antibiotics, Antitubercular: Substances obtained from various species of microorganisms that are, alone or in combination with other agents, of use in treating various forms of tuberculosis; most of these agents are merely bacteriostatic, induce resistance in the organisms, and may be toxic.BCG Vaccine: An active immunizing agent and a viable avirulent attenuated strain of Mycobacterium tuberculosis, var. bovis, which confers immunity to mycobacterial infections. It is used also in immunotherapy of neoplasms due to its stimulation of antibodies and non-specific immunity.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Macrophages: The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)Mutagenesis, Insertional: 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.Disaccharides: Oligosaccharides containing two monosaccharide units linked by a glycosidic bond.Species Specificity: 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.Mycobacteriaceae: A family of gram-positive bacteria found in soil and dairy products and as parasites on animals and man. Several are important pathogens.Bacteriological Techniques: Techniques used in studying bacteria.Mycobacterium xenopi: A slow-growing, scotochromogenic species occurring usually harmlessly in human secretions but occasionally associated with chronic pulmonary disease. (Dorland, 28th ed)Alanine-tRNA Ligase: An enzyme that activates alanine with its specific transfer RNA. EC A chronic granulomatous infection caused by MYCOBACTERIUM LEPRAE. The granulomatous lesions are manifested in the skin, the mucous membranes, and the peripheral nerves. Two polar or principal types are lepromatous and tuberculoid.Porins: Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Mannosides: Glycosides formed by the reaction of the hydroxyl group on the anomeric carbon atom of mannose with an alcohol to form an acetal. They include both alpha- and beta-mannosides.ArabinosePolymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Oxazoles: Five-membered heterocyclic ring structures containing an oxygen in the 1-position and a nitrogen in the 3-position, in distinction from ISOXAZOLES where they are at the 1,2 positions.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Dihydrostreptomycin Sulfate: A semi-synthetic aminoglycoside antibiotic that is used in the treatment of TUBERCULOSIS.Genome, Bacterial: The genetic complement of a BACTERIA as represented in its DNA.Escherichia coli: 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.Genes, Essential: Those genes found in an organism which are necessary for its viability and normal function.Transformation, Bacterial: The heritable modification of the properties of a competent bacterium by naked DNA from another source. The uptake of naked DNA is a naturally occuring phenomenon in some bacteria. It is often used as a GENE TRANSFER TECHNIQUE.Tuberculosis, Bovine: An infection of cattle caused by MYCOBACTERIUM BOVIS. It is transmissible to man and other animals.Leprostatic Agents: Substances that suppress Mycobacterium leprae, ameliorate the clinical manifestations of leprosy, and/or reduce the incidence and severity of leprous reactions.Anti-Infective Agents: Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.Plasmids: 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.AmidohydrolasesMannosyltransferases: Enzymes that catalyze the transfer of mannose from a nucleoside diphosphate mannose to an acceptor molecule which is frequently another carbohydrate. The group includes EC, EC, EC, and EC Dehydrogenase: An NAD-dependent enzyme that catalyzes the reversible DEAMINATION of L-ALANINE to PYRUVATE and AMMONIA. The enzyme is needed for growth when ALANINE is the sole CARBON or NITROGEN source. It may also play a role in CELL WALL synthesis because L-ALANINE is an important constituent of the PEPTIDOGLYCAN layer.Nicotinamidase: An enzyme that catalyzes the hydrolysis of nicotinamide to nicotinate and ammonia. EC haemophilum: A species of gram-positive, aerobic bacteria that causes granulomatous or ulcerating skin lesions in immunosuppressed persons. This organism owes its name to its requirement for growth of high levels of iron, conveniently supplied as blood, heme, or ferric ammonium citrate.TrehaloseColony Count, Microbial: Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.Open Reading Frames: 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).Acyltransferases: Enzymes from the transferase class that catalyze the transfer of acyl groups from donor to acceptor, forming either esters or amides. (From Enzyme Nomenclature 1992) EC 2.3.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Operon: 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.Pyrazinamide: A pyrazine that is used therapeutically as an antitubercular agent.DNA Gyrase: A bacterial DNA topoisomerase II that catalyzes ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. Gyrase binds to DNA as a heterotetramer consisting of two A and two B subunits. In the presence of ATP, gyrase is able to convert the relaxed circular DNA duplex into a superhelix. In the absence of ATP, supercoiled DNA is relaxed by DNA gyrase.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Kanamycin Resistance: Nonsusceptibility of bacteria to the antibiotic KANAMYCIN, which can bind to their 70S ribosomes and cause misreading of messenger RNA.Sputum: Material coughed up from the lungs and expectorated via the mouth. It contains MUCUS, cellular debris, and microorganisms. It may also contain blood or pus.Promoter Regions, Genetic: 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.Glycine Dehydrogenase: An oxidoreductase that catalyzes the oxidative DEAMINATION of GLYCINE to glyoxylate and AMMONIA in the presence of NAD. In BACTERIA lacking transaminating pathways the enzyme can act in the reverse direction to synthesize glycine from glyoxylate and ammonia and NADH.Dianisidine: Highly toxic compound which can cause skin irritation and sensitization. It is used in manufacture of azo dyes.Phagosomes: Membrane-bound cytoplasmic vesicles formed by invagination of phagocytized material. They fuse with lysosomes to form phagolysosomes in which the hydrolytic enzymes of the lysosome digest the phagocytized material.Mannose: A hexose or fermentable monosaccharide and isomer of glucose from manna, the ash Fraxinus ornus and related plants. (From Grant & Hackh's Chemical Dictionary, 5th ed & Random House Unabridged Dictionary, 2d ed)Gene Knockout Techniques: Techniques to alter a gene sequence that result in an inactivated gene, or one in which the expression can be inactivated at a chosen time during development to study the loss of function of a gene.Armadillos: Burrowing, chiefly nocturnal mammals of the family Dasypodidae having bodies and heads encased in small bony plates. They are widely distributed in the warmer parts of the Americas.Siderophores: Low-molecular-weight compounds produced by microorganisms that aid in the transport and sequestration of ferric iron. (The Encyclopedia of Molecular Biology, 1994)Bacterial Typing Techniques: Procedures for identifying types and strains of bacteria. The most frequently employed typing systems are BACTERIOPHAGE TYPING and SEROTYPING as well as bacteriocin typing and biotyping.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization: A mass spectrometric technique that is used for the analysis of large biomolecules. Analyte molecules are embedded in an excess matrix of small organic molecules that show a high resonant absorption at the laser wavelength used. The matrix absorbs the laser energy, thus inducing a soft disintegration of the sample-matrix mixture into free (gas phase) matrix and analyte molecules and molecular ions. In general, only molecular ions of the analyte molecules are produced, and almost no fragmentation occurs. This makes the method well suited for molecular weight determinations and mixture analysis.Fatty Acid Synthases: Enzymes that catalyze the synthesis of FATTY ACIDS from acetyl-CoA and malonyl-CoA derivatives.Tuberculosis, Multidrug-Resistant: Tuberculosis resistant to chemotherapy with two or more ANTITUBERCULAR AGENTS, including at least ISONIAZID and RIFAMPICIN. The problem of resistance is particularly troublesome in tuberculous OPPORTUNISTIC INFECTIONS associated with HIV INFECTIONS. It requires the use of second line drugs which are more toxic than the first line regimens. TB with isolates that have developed further resistance to at least three of the six classes of second line drugs is defined as EXTENSIVELY DRUG-RESISTANT TUBERCULOSIS.Kinetics: The rate dynamics in chemical or physical systems.Virulence: The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.Nitroreductases: Enzymes which reduce nitro groups (NITRO COMPOUNDS) and other nitrogenous compounds.

RecA-Mediated gene conversion and aminoglycoside resistance in strains heterozygous for rRNA. (1/838)

Clinical resistance to aminoglycosides in general is due to enzymatic drug modification. Mutational alterations of the small ribosomal subunit rRNA have recently been found to mediate acquired resistance in bacterial pathogens in vivo. In this study we investigated the effect of 16S rRNA heterozygosity (wild-type [wt] and mutant [mut] operons at position 1408 [1408wt/1408mut]) on aminoglycoside resistance. Using an integrative vector, we introduced a single copy of a mutated rRNA operon (1408 A-->G) into Mycobacterium smegmatis, which carries two chromosomal wild-type rRNA operons; the resultant transformants exhibited an aminoglycoside-sensitive phenotype. In contrast, introduction of the mutated rRNA operon into an M. smegmatis rrnB knockout strain carrying a single functional chromosomal wild-type rRNA operon resulted in aminoglycoside-resistant transformants. Subsequent analysis by DNA sequencing and RNase protection assays unexpectedly demonstrated a homozygous mutant genotype, rRNAmut/rRNAmut, in the resistant transformants. To investigate whether RecA-mediated gene conversion was responsible for the aminoglycoside-resistant phenotype in the rRNAwt/rRNAmut strains, recA mutant strains were generated by allelic exchange techniques. Transformation of the recA rrnB M. smegmatis mutant strains with an integrative vector expressing a mutated rRNA operon (Escherichia coli position 1408 A-->G) resulted in transformants with an aminoglycoside-sensitive phenotype. Subsequent analysis showed stable heterozygosity at 16S rRNA position 1408 with a single wild-type allele and a single resistant allele. These results demonstrate that rRNA-mediated mutational resistance to aminoglycosides is recessive.  (+info)

Genetic evidence that InhA of Mycobacterium smegmatis is a target for triclosan. (2/838)

Three Mycobacterium smegmatis mutants selected for resistance to triclosan each had a different mutation in InhA, an enoyl reductase involved in fatty acid synthesis. Two expressed some isoniazid resistance. A mutation originally selected on isoniazid also mediated triclosan resistance, as did the wild-type inhA gene on a multicopy plasmid. Replacement of the mutant chromosomal inhA genes with wild-type inhA eliminated resistance. These results suggest that M. smegmatis InhA, like its Escherichia coli homolog FabI, is a target for triclosan.  (+info)

Role of acid pH and deficient efflux of pyrazinoic acid in unique susceptibility of Mycobacterium tuberculosis to pyrazinamide. (3/838)

Pyrazinamide (PZA) is an important antituberculosis drug. Unlike most antibacterial agents, PZA, despite its remarkable in vivo activity, has no activity against Mycobacterium tuberculosis in vitro except at an acidic pH. M. tuberculosis is uniquely susceptible to PZA, but other mycobacteria as well as nonmycobacteria are intrinsically resistant. The role of acidic pH in PZA action and the basis for the unique PZA susceptibility of M. tuberculosis are unknown. We found that in M. tuberculosis, acidic pH enhanced the intracellular accumulation of pyrazinoic acid (POA), the active derivative of PZA, after conversion of PZA by pyrazinamidase. In contrast, at neutral or alkaline pH, POA was mainly found outside M. tuberculosis cells. PZA-resistant M. tuberculosis complex organisms did not convert PZA into POA. Unlike M. tuberculosis, intrinsically PZA-resistant M. smegmatis converted PZA into POA, but it did not accumulate POA even at an acidic pH, due to a very active POA efflux mechanism. We propose that a deficient POA efflux mechanism underlies the unique susceptibility of M. tuberculosis to PZA and that the natural PZA resistance of M. smegmatis is due to a highly active efflux pump. These findings may have implications with regard to the design of new antimycobacterial drugs.  (+info)

A mutant of Mycobacterium smegmatis defective in the biosynthesis of mycolic acids accumulates meromycolates. (4/838)

Mycolic acids are a major constituent of the mycobacterial cell wall, and they form an effective permeability barrier to protect mycobacteria from antimicrobial agents. Although the chemical structures of mycolic acids are well established, little is known on their biosynthesis. We have isolated a mycolate-deficient mutant strain of Mycobacterium smegmatis mc2-155 by chemical mutagenesis followed by screening for increased sensitivity to novobiocin. This mutant also was hypersensitive to other hydrophobic compounds such as crystal violet, rifampicin, and erythromycin. Entry of hydrophobic probes into mutant cells occurred much more rapidly than that into the wild-type cells. HPLC and TLC analysis of fatty acid composition after saponification showed that the mutant failed to synthesize full-length mycolic acids. Instead, it accumulated a series of long-chain fatty acids, which were not detected in the wild-type strain. Analysis by 1H NMR, electrospray and electron impact mass spectroscopy, and permanganate cleavage of double bonds showed that these compounds corresponded to the incomplete meromycolate chain of mycolic acids, except for the presence of a beta-hydroxyl group. This direct identification of meromycolates as precursors of mycolic acids provides a strong support for the previously proposed pathway for mycolic acid biosynthesis involving the separate synthesis of meromycolate chain and the alpha-branch of mycolic acids, followed by the joining of these two branches.  (+info)

Integron-mediated rifampin resistance in Pseudomonas aeruginosa. (5/838)

A new rifampin resistance gene, arr-2, has been found in Pseudomonas aeruginosa. The ARR-2 protein shows 54% amino acid identity to the rifampin ADP-ribosylating transferase encoded by the arr gene from Mycobacterium smegmatis. This arr-2 gene is located on a gene cassette within a class I integron.  (+info)

Apoptosis of Mycobacterium avium-infected macrophages is mediated by both tumour necrosis factor (TNF) and Fas, and involves the activation of caspases. (6/838)

Mycobacterium avium causes disseminated infection in AIDS patients and several forms of infection in immunocompetent hosts. Recent studies have shown that M. avium infection of macrophages in vitro leads to apoptosis of significant numbers of infected cells. Several strains of M. avium used to infect human macrophages for 5 days (multiplicity of infection of 10) triggered 28-46% higher levels of apoptosis than observed with uninfected macrophages at the same time points. Mycobacterium avium strains unable to replicate intracellularly (rep-) resulted in a 15% rate of apoptosis, while M. smegmatis-infected monolayers showed the same percentage of apoptotic cells as the uninfected macrophage control. The presence of anti-TNF-alpha antibody reduced apoptosis to 17% and the presence of anti-Fas antibody reduced apoptosis to 10%. When both antibodies were used together, the apoptosis level was 5% above the control. Treatment with TGF-beta also reduced the number of apoptotic cells in infected monolayers. If intracellular growth was inhibited, apoptosis of macrophages decreased significantly. It was also shown that apoptosis was associated with IL-1 beta-converting enzyme (ICE) activation and was significantly reduced by a caspase inhibitor. Gaining understanding of the mechanisms of M. avium-associated apoptosis of macrophages will provide important insight into M. avium pathogenesis.  (+info)

Enhanced gene replacement in mycobacteria. (7/838)

Allelic replacement will be a vital tool for understanding gene function in mycobacteria. Disruption of the chromosomal hisD gene of Mycobacterium smegmatis by standard gene replacement methods was surprisingly difficult, with most products being caused by illegitimate recombination (IR) events. A recombination assay was therefore developed and used to optimize conditions for homologous recombination (HR) in M. smegmatis. Treatment of competent cells with UV, hydrogen peroxide or mitomycin C did not improve the frequency of HR; however, treatment of the DNA with alkali or UV enhanced recombination frequency, while boiling did not. Applying these observations to allele replacement, UV and alkali treatment of transforming DNA increased HR events with pyrF and hisD, while the level of IR was unchanged. The introduction of ss phagemid DNA improved the level of HR and abolished IR. In Mycobacterium intracellulare the use of alkali-denatured DNA increased the numbers of recombinants obtained with an inactivated 19Ag gene, while in Mycobacterium tuberculosis, inactivation of a putative haemolysin gene, tlyA, was achieved using both UV-irradiated DNA and ss phagemid DNA. Significantly, IR, which has been reported to be a problem in this species, was not observed. Thus, four genes in three species were successfully knocked-out using non-replicating DNA pretreated with alkali, UV or in an ss form. The use of these methods to enhance HR will greatly facilitate experiments to inactivate other genes in these important species.  (+info)

Enhancing the immunotherapeutic potential of mycobacteria by transfection with tumour necrosis factor-alpha. (8/838)

In an attempt to enhance the anti-tumour properties of mycobacteria we have developed recombinant forms of Mycobacterium smegmatis which express and secrete biologically active human tumour necrosis factor-alpha (TNF-alpha). This was achieved by transfecting M. smegmatis using shuttle plasmids incorporating the cDNA sequence for the human TNF-alpha mature peptide. In vitro experiments on a panel of human bladder tumour cell lines (EJ18, MGH-U1, RT4, RT112) indicate that our genetically modified mycobacteria are more effective than wild-type at inducing or up-regulating the expression of intracellular adhesion molecule-1 and the secretion of an array of proinflammatory cytokines [interleukin-1 (IL-1), IL-6, IL-8, granulocyte-macrophage colony-stimulating factor]. We have also demonstrated increased adhesion molecule and cytokine expression in response to mycobacteria transfected with vector containing no gene insert. However, this was not as pronounced as that observed following tumour cell stimulation by the TNF-alpha-transfected strain. In contrast, in three out of four tumour cell lines all M. smegmatis strains were found to down-regulate the secretion of the anti-inflammatory cytokine transforming growth factor-beta1. Our studies have also confirmed that M. smegmatis is a powerful inhibitor of bladder tumour cell growth and revealed that its antiproliferative potency is enhanced by transfecting with human TNF-alpha and, to a lesser extent, with vector alone. All M. smegmatis strains were effective in the activation of peripheral blood leucocyte cultures. However, no differences were observed in the ability of the TNF-alpha-transfected, mock-transfected and wild-type mycobacteria to induce tumour cell killing activity. These results suggest that the immunomodulatory effects of M. smegmatis can be enhanced by transfection with vectors which allow the secretion of human TNF-alpha, thus increasing mycobacterial immunotherapeutic potential.  (+info)

  • There remains a paucity of information regarding ion homeostasis networks and pathways in mycobacteria. (
  • Disruption of potassium homeostasis in the ΔtrkA mutant of M. smegmatis resulted in the reduction of (~10-50%) intracellular potassium concentrations and elevated (~10-30%) intracellular sodium concentrations, coupled with reductions in viability and persistence under hypoxia. (
  • This study has demonstrated the molecular inventory of intracellular ions in M. smegmatis under several key laboratory conditions and has characterised essential components of ion homeostasis and more specifically, potassium homeostasis and energetics in mycobacteria. (
  • Mycobacteria are part of the native microflora found in soils and aquatic environments and harbour an extensive repertoire of uptake and efflux and secretion pathways to modulate ions and metabolites including, sodium, potassium, calcium, magnesium, iron, nickel, manganese, zinc, copper and cobalt. (
  • Inductively coupled plasma mass spectroscopy (ICP-MS) analysis of wild-type M. smegmatis and energy-driven ion transport mutants revealed the molecular inventory of cations in M. smegmatis under normoxia and hypoxia. (
  • The intracellular cation profile of M. smegmatis was comprised primarily of sodium (40-85%), potassium (10-55%) and magnesium (5-7%), while trace elements consisting of calcium, iron, nickel, manganese, zinc, copper and cobalt were less than 1.5% of the profile. (
  • This study explores the potential use of computational models to characterize the sites targeted by VapC in Mycobacterium smegmatis. (
  • Comparison of different methods for thin section EM analysis of Mycobacterium smegmatis. (
  • General Significance - This study highlights how the lowering of flux through the GlgE pathway can slow the growth mycobacteria. (
  • These observations lend support to the hypothesis that the strong induction of the innate immune response is a major reason for the lack of pathogenicity in fast-growing mycobacteria. (
  • Convit, J.: Electron microscope study of Mycobacterium leprae and its environment in a vesicular leprous lesion. (
  • The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. (
  • By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae. (
  • Mutation accumulation experiments of M. smegmatis yielded a base-substitution mutation rate of 5.27 × 10 −10 per site per generation, or 0.0036 per genome per generation, which is surprisingly similar to the mutation rate in MMR-functional unicellular organisms. (
  • We also found that the transition-mutation rate of M. smegmatis is significantly lower than that of other naturally MMR-devoid or MMR-knockout organisms. (
  • The mutation features of M. smegmatis provide further evidence that genomes harbor alternative routes for improving replication fidelity, even in the absence of major repair pathways. (
  • However, a complex plasmid swapping strategy was required to generate the Δ phoU1 Δ phoU2 mutant, suggesting that either phoU1 or phoU2 is essential for in vitro growth of M. smegmatis . (
  • Deletion of egtD from wild-type M. smegmatis and an MSH-deficient mutant did not affect their susceptibility to antibiotics tested in this study. (
  • An unmarked deletion mutant in pitA of M. smegmatis was created. (
  • However, increased expression of the remaining phosphate transporters in the mutant indicates a compensatory mechanism and implies that PitA is indeed used for the uptake of phosphate in M. smegmatis. (
  • We investigated the role of GlnR in the nitrogen limitation response and determined the entire GlnR regulon , by combining expression profiling of M. smegmatis wild type and glnR deletion mutant, with GlnR-specific chromatin immunoprecipitation and high throughput sequencing. (
  • In this study, we demonstrate that the M. smegmatis alr insertion mutant TAM23 can synthesize d-alanine at lower levels than the parental strain. (
  • My data suggest that a ∆cadC mutant is defective in the generation or replenishment of intracellular lysine and DAP levels that are essential for growth and survival in mycobacteria. (
  • Here we show that Mycobacterium smegmatis MmpL3 mutant strains had an altered cell wall hydrophobicity, disrupted membrane potential and growth defects in liquid media. (
  • M. smegmatis MmpL3 mutant strains were resistant to two anti-tubercular agents, SQ109 and AU1235, but were more sensitive to rifampicin, erythromycin and ampicillin. (
  • In this study, transcriptomic analysis (RNA-seq) of an M. smegmatis Δ prrAB mutant was used to define the PrrAB regulon and provide insights into the essential nature of PrrAB in M. tuberculosis . (
  • Disruption of potassium homeostasis in the ΔtrkA mutant of M. smegmatis resulted in the reduction of (~10-50%) intracellular potassium concentrations and elevated (~10-30%) intracellular sodium concentrations, coupled with reductions in viability and persistence under hypoxia. (
  • The M. smegmatis alr insertion mutant TAM23 exhibited essentially identical growth to wild-type mc 2 155 in the absence of d-alanine. (
  • In addition, we have demonstrated that a double deletion mutant M. smegmatis MS6039-5941 [DMSMEG_6039 (DkshB1) and DMSMEG_5941 (DkstD1)] transforms natural sterols into 4-androstene-3,17-dione with high yields. (
  • Use of a number of PAF C-16 structural analogs, including Lyso-PAF, 2-O-methyl PAF, PAF C-18 and Hexanolamino PAF, revealed that the presence of acetyl group (CH 3 CO) at sn -2 position of the glycerol backbone of PAF is important for the intracellular growth inhibition activity against M. smegmatis . (
  • Because of this, Mycobacterium tuberculosis (Mtb) is more rapidly killed using a combination of drugs capable of PBP- and LDT- inhibition. (
  • Addgene: The Phn system of Mycobacterium smegmatis: a second high-affinity ABC-transporter for phosphate. (
  • Furthermore, I showed that M. smegmatis has a high-affinity lysine uptake system that exhibited high rates of lysine transport during growth in minimal medium, which was significantly reduced during growth in rich medium. (
  • The present study was directed at investigating the role of the low-affinity phosphate transporter in a bacterium containing at least two high-affinity systems, using the model of M. smegmatis . (
  • Conjugal DNA transfer in M. smegmatis requires stable and extended contact between a donor and a recipient strain, is DNase resistant, and the transferred DNA is incorporated into the recipient's chromosome by homologous recombination. (
  • These findings suggest that the catabolism of cholesterol in M. smegmatis mc2155 is easy to handle and equally efficient for sterol transformation than other industrial strains, paving the way for valuating this strain as a suitable industrial cell factory to develop a la carte metabolic engineering strategies for the industrial production of pharmaceutical steroids. (
  • A detailed biochemical analysis of PhnF binding to its identified binding sites in the phnD-phnF intergenic region of M. smegmatis has allowed us to propose a quantitative model for repressor binding, which shows that a PhnF dimer binds independently to each site. (
  • The specialized secretory apparatus ESX-1 is essential for DNA transfer in Mycobacterium smegmatis. (
  • This study has demonstrated the molecular inventory of intracellular ions in M. smegmatis under several key laboratory conditions and has characterised essential components of ion homeostasis and more specifically, potassium homeostasis and energetics in mycobacteria. (
  • Our results provide further support for the hypothesis that Alr is not an essential function of M. smegmatis and that specific Alr inhibitors will have no bactericidal action. (
  • Nontuberculous mycobacteria are ubiquitous and saprophytic organisms that have been implicated in a wide spectrum of diseases due to an increasing number of immunocompromised patients . (
  • The kinetic properties of the M. smegmatis enzyme were also similar to known prokaryotic methionine adenosyltransferases. (
  • We show that abrogation of Ung activity in P. aeruginosa and M. smegmatis confers upon them an increased mutator phenotype and sensitivity to reactive nitrogen intermediates generated by acidified nitrite. (
  • Conjugal DNA transfer in Mycobacterium smegmatis occurs by a mechanism distinct from plasmid-mediated DNA transfer. (
  • To date, the acetamide-inducible system of Mycobacterium smegmatis has been the most widely used controllable promoter in mycobacteria ( 7 , 20 ). (