The catalase-peroxidase of Mycobacterium intracellulare: nucleotide sequence analysis and expression in Escherichia coli

The activation of catalase genes in response to oxidative stress may contribute to the intracellular survival of mycobacteria. In this report, the nucleotide sequence of a mycobacterial catalase gene is described. The deduced protein sequence of this Mycobacterium intracellulare gene (M185) was 60% identical to the Escherichia coli hydroperoxidase I (HPI) protein, 59% identical to the Salmonella typhimurium (HPI) catalase, and 47% identical to a Bacillus stearothermophilus peroxidase. The M185 protein, expressed in E. coli, has also been shown to have peroxidase and catalase activities. Furthermore, Southern blot hybridizations, which demonstrated that a M185 gene probe hybridizes with chromosomal DNA from thirteen different strains of mycobacteria, suggest that this catalase-peroxidase gene is prevalent in the mycobacterial genus. The availability of catalase gene probes should permit an evaluation, at the molecular level, of the role of catalase in mycobacterial pathogenesis.