Methionine Aminopeptidases from Mycobacterium tuberculosis as Novel Antimycobacterial Targets

SummaryMethionine aminopeptidase (MetAP) is a metalloprotease that removes the N-terminal methionine during protein synthesis. To assess the importance of the two MetAPs in Mycobacterium tuberculosis, we overexpressed and purified each of the MetAPs to near homogeneity and showed that both were active as MetAP enzymes in vitro. We screened a library of 175,000 compounds against MtMetAP1c and identified 2,3-dichloro-1,4-naphthoquinone class of compounds as inhibitors of both MtMetAPs. It was found that the MtMetAP inhibitors were active against replicating and aged nongrowing M. tuberculosis. Overexpression of either MtMetAP1a or MtMetAP1c in M. tuberculosis conferred resistance of bacterial cells to the inhibitors. Moreover, knockdown of MtMetAP1a, but not MtMetAP1c, resulted in decreased viability of M. tuberculosis. These results suggest that MtMetAP1a is a promising target for developing antituberculosis agents.

► Expressed, purified, and characterized two isoforms of methionine aminopeptidase from mycobacterium tuberculosis
► Performed high-throughput screening using one of the isozymes
► Identified a new family of small molecular inhibitors that inhibited bacterial growth
► Validated the enzyme as the target for inhibition of the bacteria by the newly identified inhibitors