Members of the high temperature requirement A (HtrA) family of chaperone proteases have been shown to play a
role in bacterial pathogenesis. In a recent report, we demonstrated that the gene ML0176, which codes for a predicted
HtrA-like protease, a gene conserved in other species of mycobacteria, is transcribed by
human leprosy lesions. In the present study, the recombinant ML0176 protein was produced and its enzymatic properties
investigated. M. leprae
recombinant ML0176 was able to hydrolyse a variety of synthetic and natural peptides.
Similar to other HtrA proteins, this enzyme displayed maximum proteolytic activity at temperatures above 40°C and
was completely inactivated by aprotinin, a protease inhibitor with high selectivity for serine proteases. Finally, analysis
of M. leprae
ML0176 specificity suggested a broader cleavage preference than that of previously described HtrAs
homologues. In summary, we have identified an HtrA-like protease in M. leprae
that may constitute a potential new
target for the development of novel prophylactic and/or therapeutic strategies against mycobacterial infections.