Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors examined the possibility of detecting M. tuberculosis cells in various types of diagnostic material (sputum, blood, bone marrow, bronchoalveolar lavage fluid) from tuberculosis patients using polymerase chain reaction (PCR). The developed PCR-based test systems helped detect M. tuberculosis in 48 (90.6%) out of 53 tuberculosis patients, in contrast to much slower microbiological methods which permitted detection of Mycobacteria in only 21 (39.6%) patients. High specificity and virtually no false-positive results of PCR were demonstrated in testing diagnostic material from patients with chronic nonspecific pulmonary diseases and from children with lympholeukemia and anemia.
Mol Gen Mikrobiol Virusol
PMID:[Identification of tuberculosis pathogens in clinical material using the polymerase chain reaction]. 760 90

Isoniazid (INH) resistance of the Mycobacterium tuberculosis Complex (MtbC) is associated with both loss of catalase activity and mutation of the inhA gene. However, the relative contributions of these changes to resistance and to the loss of virulence for guinea-pigs is unknown. In this study, a virulent strain of Mycobacterium bovis, a member of the MtbC, was exposed to increasing concentrations of INH. Two INH-resistant strains were produced which had lost catalase activity. Strain WAg405, which had a higher resistance to INH, also had a mutation in the inhA gene. This demonstrated that loss of catalase activity and mutation of inhA had a cumulative effect on INH resistance. When a functional katG gene was integrated into the genome of WAg405 the INH resistance was greatly reduced. This indicated that most of the resistance had been caused by loss of catalase activity. While the parent INH-sensitive strain was virulent for guinea-pigs, the INH-resistant strains were significantly less virulent. Integration of a functional katG gene into the most resistant strain restored full virulence. This clearly established that katG is a virulence factor for M. bovis and that mutation of the inhA gene has no effect on virulence.
Mol Microbiol 1995 Mar
PMID:Effect of inhA and katG on isoniazid resistance and virulence of Mycobacterium bovis. 762 58

The cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) are released by mononuclear phagocytes in vitro after stimulation with mycobacteria and are considered to mediate pathophysiologic events, including granuloma formation and systemic symptoms. We demonstrated that the Mycobacterium tuberculosis cell wall component lipoarabinomannan (LAM) is a very potent inducer of IL-1 beta gene expression in human monocytes and investigated the mechanism of this effect. We localized the LAM-, lipopolysaccharide (LPS)-, and TNF-alpha-inducible promoter activity to a -131/+15 (positions -131 to +15) DNA fragment of the IL-1 beta gene by deletion analysis and chloramphenicol acetyltransferase assay. Within this DNA fragment, there were two novel 9-bp motifs (-90/-82 and -40/-32) with high homology to the nuclear factor-IL6 (NF-IL6) binding site. Site-directed mutagenesis demonstrated that the two NF-IL-6 motifs could be independently activated by LAM, LPS, or TNF-alpha and that they acted in an orientation-independent manner. DNA mobility shift assay revealed specific binding of nuclear protein(s) from LAM-, LPS-, or TNF-alpha-stimulated THP-1 cells to the NF-IL6 motifs. We conclude that the two NF-IL6 sites mediate induction of IL-1 beta in response to the stimuli LAM, LPS, and TNF-alpha.
Mol Cell Biol 1993 Jun
PMID:Regulation of the interleukin-1 beta (IL-1 beta) gene by mycobacterial components and lipopolysaccharide is mediated by two nuclear factor-IL6 motifs. 768 3

The toxicity of the powerful anti-tuberculosis drug isoniazid (INH) is believed to be mediated by the haem-containing enzyme catalase-peroxidase, encoded by the katG gene of Mycobacterium tuberculosis. Compelling evidence for this was obtained by studying a panel of INH-resistant clinical isolates using a novel strategy based on the polymerase chain reaction and single-strand-conformation polymorphism analysis (PCR-SSCP) to detect mutations in katG. In most cases INH resistance was associated with missense mutations while in a small number of strains the gene had been completely, or partially, deleted. The missense mutations fell into two groups, the larger of which contained several independent mutations that affected the N-terminal peroxidase domain of the protein, resulting in the production of a catalase peroxidase with strongly reduced enzyme activity and increased heat liability. The effects of these substitutions could be interpreted by means of molecular modelling using the crystal structure of the related enzyme cytochrome c peroxidase from yeast as a template. The second group comprises a frequently occurring amino acid substitution and a single mutation that are both located in the C-terminal domain but do not noticeably alter either enzyme activity or heat stability.
Mol Microbiol 1995 Jan
PMID:Missense mutations in the catalase-peroxidase gene, katG, are associated with isoniazid resistance in Mycobacterium tuberculosis. 774 45

Southern blot analysis of chromosomal DNA from clinical isolates of Mycobacterium tuberculosis using cosmid DNA probes revealed extensive strain variation in the katG region of the genome. In addition to deletion of the katG gene itself in some isoniazid-resistant strains, adjacent DNA fragments were missing or altered in a range of drug-sensitive and drug-resistant isolates. A species-specific 2kb Kpnl fragment located 10kb upstream of katG in M. tuberculosis H37Rv hybridized to fragments of differing size in different clinical isolates and was characterized in detail. Sequence analysis of this fragment in detail. Sequence analysis of this fragment showed that it comprised three tandem copies of a novel 75 bp repeat element flanked by multiple copies of the previously described 10 bp major polymorphic tandem repeat of M. tuberculosis (MPTR). The copy number of the 75 bp repeat was found to vary between strains, allowing application of a polymerase chain reaction amplification strategy for strain differentiation. These results indicate that the katG region of the M. tuberculosis genome is highly variable and unstable. The presence of repetitive sequences may contribute to instability in this region of the genome.
Mol Microbiol 1994 Oct
PMID:Strain variation in the katG region of Mycobacterium tuberculosis. 783 May 74

Understanding promoter regulation and signal-transduction systems in pathogenic mycobacteria is critical for uncovering the processes that govern interactions of these bacteria with the human host. In order to develop additional genetic tools for analysis of mycobacterial promoters, the xyIE gene from Pseudomonas was tested as a transcriptional fusion reporter in fast- and slow-growing mycobacteria. Initially, its utility was demonstrated by expression behind the hsp60 promoter in Mycobacterium smegmatis and Mycobacterium bovis BCG. The presence of an active promoter in front of the promoterless xyIE cassette on a plasmid was scored by development of a bright yellow colour upon spraying of mycobacterial colonies on plates with a solution of catechol. The gene product of xyIE, catechol 2,3 dioxygenase, was measurable in sonic extracts and whole cells, permitting quantitative determination of promoter activity in both fast- and slow-growing mycobacteria. The xyIE-based mycobacterial transcriptional fusion plasmid pRCX3 was constructed and used to assess promoter activity within the sequences located upstream of the newly characterized Mycobacterium tuberculosis H37Rv response regulator mtrA, a member of the superfamily of bacterial signal-transduction systems.
Mol Microbiol 1994 Sep
PMID:Gene expression in mycobacteria: transcriptional fusions based on xylE and analysis of the promoter region of the response regulator mtrA from Mycobacterium tuberculosis. 785 20

Triplex-polymerase chain reaction technique (PCR) was developed for the detection and identification of mycobacterial DNA sequences in uncultured clinical samples. A 123 bp fragment corresponding to a specific Mycobacterium tuberculosis sequence complex, a 383 bp DNA fragment encoding for part of the 65 kD mycobacterial surface antigen, and a 268 bp fragment of the human beta-globin gene to demonstrate the presence of suitable DNA were amplified by triplex PCR. To demonstrate the applicability of this method, 206 alcohol-fixed, paraffin-embedded sputum samples from 47 patients with culture-proven tuberculosis were investigated. Of 206 samples, 157 were PCR positive, resulting in correct diagnosis of tuberculosis in 46 of 47 (97.8%) patients. Furthermore, 165 alcohol-fixed, auramin-stained sputum smears were examined in a blind trial. Triplex PCR revealed tuberculosis in 20 of 21 samples from patients with tuberculosis. In comparison, cultures were positive in 20 of 21 samples, and acid-fast organisms were found by microscopy in 18 of 21 samples. We conclude that triplex PCR is a rapid and sensitive technique for the detection of mycobacterial DNA in uncultured clinical samples and offers equivalent sensitivity (95.2%) and specificity (98.6%) as do culture methods.
Diagn Mol Pathol 1994 Dec
PMID:Rapid detection of mycobacterial DNA in clinical samples by multiplex PCR. 786 36

The X-ray structure of the tetrameric iron-dependent superoxide dismutase from Mycobacterium tuberculosis has been refined to an R-factor of 0.167 and a correlation coefficient of 0.954 at 2.0 A resolution. The crystals are monoclinic P2(1) and have four subunits related by strong non-crystallographic 222 (or D2) symmetry in the asymmetric unit. 198 of the 207 amino acids of each subunit are defined by the electron density which shows that they adopt the conserved fold of other iron- or manganese-dependent SODs. The structure can be divided into two domains, the N-terminal domain involving an extended region followed by two projecting antiparallel alpha-helices, and the C-terminal domain containing four more helical segments with a three-stranded antiparallel beta-sheet inserted sequentially between the fourth and fifth helices. The catalytic iron is co-ordinated by five ligands: three histidines (residues 28, 76 and 164), one aspartate (160) and a solvent molecule. The inferred positions of protons at the active site are consistent with the solvent ligand being a hydroxide ion. This ligand interacts with His145 in the Mycobacterium tuberculosis SOD. In the highly homologous Mycobacterium leprae Mn-SOD, the histidine is replaced by glutamine, this being the only significant residue difference within 10 A of the Fe3+. The nature of the amino acid at this position may influence the metal ion specificity of these enzymes. The subunits of the Mycobacterium tuberculosis SOD associate by polar contacts to form dimers, which closely resemble those of other dimeric or tetrameric Fe- or Mn-SODs. However, the dimer-dimer interactions within the tetramer are novel, being dominated by dimerisation of the 144 to 152 loop regions which connect the outer two beta-strands of the three-membered beta-sheet. This contrasts strongly with the other tetrameric Fe- or Mn-SODs where the dimer-dimer association is dominated by the projecting alpha alpha-turn in the N-terminal domain.
J Mol Biol 1995 Mar 03
PMID:X-ray structure analysis of the iron-dependent superoxide dismutase from Mycobacterium tuberculosis at 2.0 Angstroms resolution reveals novel dimer-dimer interactions. 787 74

We isolated and determined the nucleotide sequence of the 70K gene from nine mycobacteria and from two related non-mycobacteria with the goal of obtaining a region of requisite specificity to serve as a mycobacterial genus-specific probe. Two different primer sets were then designed to amplify the 70K gene using strand displacement amplification. Using one of the primer sets, 10 different mycobacteria were readily detected with sensitivities of 100 molecules DNA, and with only cross-reactivity to two non-mycobacteria. The other set of primers that were tested amplified the same set of mycobacteria, but exhibited no crossreactivity with non-mycobacterial DNAs. By employing one of the primer sets, we were able to successfully amplify with high sensitivity three different target DNA sequences comprised of the 70K mycobacterial genus target, an IS 6110 (M. tuberculosis complex) target, and an internal amplification control using SDA. These results demonstrate the potential of the 70K gene to serve as a mycobacterial genus-specific probe, and demonstrate the first multiplex amplification by SDA of three DNA targets.
Mol Cell Probes 1994 Oct
PMID:Nucleotide sequence and strand displacement amplification of the 70K protein gene from mycobacteria. 787 33

We describe experiments comparing use of different DNA probes to detect mycobacteria in clinical specimens after PCR. The objective was to assess correlation between results using Mycobacterium genus-specific, and species-specific M. tuberculosis probes. Given sufficient concordance, sequential use of such probes would provide a useful screening tool. An evaluation of genus-specific probes compared use of repetitive sequences in the clone pMAv17 with the 65-kDa sequences. Sensitivity was 100% for pMAv17, 93% using the 65-kDa sequence; specificity was 70% for both. We then compared M. tuberculosis-specific probes developed by us (Tb400) with IS6110 and mpt40. Sensitivity using Tb400 was 100%; using IS6110 was 97%, and using mpt40 was 50%. Specificity using Tb400 and IS6110 was 68%, and was 70% using mpt40. Fourteen specimens which were PCR-positive and culture-negative, were positive using both genus probes, and the M. tuberculosis-specific probes Tb400, and IS6110. Ten of these were positive using mpt40.
Mol Cell Probes 1994 Oct
PMID:Comparison of genus- and species-specific probes for PCR detection of mycobacterial infections. 787 37


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