Nine structural genes (furA, katG, inhA, kasA, Rv0340, iniB, iniA, iniC, and efpA) and two regulatory regions (the oxyR-ahpC intergenic region and the promoter of mabA-inhA) in 87 isoniazid (INH)-monoresistant and 50 INH-susceptible Mycobacterium tuberculosis isolates collected from five provinces of China were analyzed by sequencing. Eighty-two (94.3%) INH-resistant isolates had mutations in t...

In several bacteria, the catalase-peroxidase gene katG is under positive control by oxyR, a transcriptional regulator of the peroxide stress response. The Mycobacterium tuberculosis genome also contains sequences corresponding to oxyR, but this gene has been inactivated in the tubercle bacillus because of the presence of multiple mutations and deletions. Thus, M. tuberculosis katG and possibly ...

2. Molecular testing based on katG and rpoB enabled rapid detection of Mycobacterium tuberculosis resistance in 46.8% and 87.5% of patients infected with isoniazidand rifampicinresistant strains, respectively. The same number of patients infected with resistant strains with mutations in katG and rpoB were detected using the MTBDRplus line probe assay. The combined use of katG and inhA regulator...

Ethionamide (ETH) is a structural analog of the antituberculosis drug isoniazid (INH). Both of these drugs target InhA, an enzyme involved in mycolic acid biosynthesis. INH requires catalase-peroxidase (KatG) activation, and mutations in katG are a major INH resistance mechanism. Recently an enzyme (EthA) capable of activating ETH has been identified. We sequenced the entire ethA structural gen...

Isoniazid (INH) activation in vitro is associated with reduction of the mycobacterial ferric KatG catalase-peroxidase by hydrazine and reaction with O2 to form an oxyferrous enzyme complex. Since this complex could also form directly via reaction of ferric KatG with superoxide, intracellular activation might be responsive to superoxide concentration. When Mycobacterium smegmatis carrying the M....

Title of Document: A NEW INSIGHT INTO MYCOBACTERIUM RESISTANCE TO REACTIVE OXYGEN INTERMEDIATES. Rabab Kish, Master of Science, 2006 Directed By: Dr. Lian-Yong Gao, Department of Cell Biology & Molecular Genetics The genes encoded by the RD1 locus are known to be important for intracellular survival of pathogenic mycobacterium, however their role in counteracting host defense is not known. I hy...

In this study, a battery of oligonucleotides was directed toward the katG gene and PCR-single-stranded conformation polymorphism (SSCP) analysis was used to search for katG gene deviations in clinical isolates of Mycobacterium tuberculosis from different geographical regions. Since a complete deletion of the katG gene was not found, it is suggested that deletion is not a major mechanism of ison...

Mutation at codon 315 of katG gene is the major cause for isoniazid (INH) resistance in Mycobacterium tuberculosis (M. tuberculosis). Substitution at codon 315 of katG gene was analyzed in 85 phenotypically resistant isolates collected from various parts of southern India by direct sequencing method. The obtained results were interpreted in the context of minimum inhibitory concentration (MIC) ...

It has long been known that almost all isoniazid (INH) resistant mycobacteria lose the catalase and peroxidase activities along with reduced or no virulence for guinea pigs. Recently resistance to INH has become known to be associated with mutations of katG gene encoding the HPI (Hydroperoxidase I) type catalase and peroxidase. Among these mutations, the point mutation of codon 463 of katG gene...

In a previous study, katE complementation of an E. coli katG mutant suggested that an overexpression of katE was the cause for low survival after UV-A treatment. In this study, when JW strains lacked either katE or katG were complemented with katE, this overexpression was not observed. Rather, there were no differences between the two complemented JW strains after UV-A treatment. A possible the...