Abstract

The MPB64 protein of Mycobacterium tuberculosis (M.tb) is an important structural and functional protein, which has been known to be involved in the virulence, pathogenesis as well as proliferation of the pathogen, however, how MPB64 protein interaction with host protein is still unclear. To identify cellular proteins that interact with the MPB64 protein and to elucidate the possible involvement of MPB64 protein in M.tb pathogenesis, a human lung cDNA library was screened using a yeast two-hybrid system assay. HSP40, a molecular chaperone facilitating protein the folding and assembly, was found to interact specifically with the MPB64 protein. The interaction between MPB64 and HSP40 was verified by colocalization experiment and coimmunoprecipitation of HeLa cell lysates expressing both proteins. The mapping studies localized the critical MPB64 sequences for this interaction to amino acid 171-206. Based on these results, we speculate that HSP40 is a functional target of M. tuberculosis MPB64 protein in cells. This is the first report demonstrating the interaction of HSP40 with a structural protein of M. tuberculosis,indicating a new drug target for M.tb.

Key words: MPB64 protein, HSP40 protein, Mycobacterium tuberculosis, yeast two-hybrid, co-immunoprecipitation, protein-protein interaction.