A rufomycin analogue is an anti-tuberculosis drug lead targeting CLPC1 with no cross resistance to ecumicin

Our recent efforts at finding new anti-tuberculosis drug leads from actinomycetes have led to the discovery of ecumicin (ECU, MW 1599.22, MIC 0.16 uM) and; more recently, a rufomycin analogue (RUF-I, MW 1041.55, MIC 0.019 uM). Although both of these cyclic peptides target the currently unexploited chaperone protein ClpC1 ATPase complex, there is no observed cross resistance. In this study, the structures of RUF-I and other rufomycin analogues, heptapeptides, were elucidated by ¹H, ¹³C, 2D NMR, MS and HiFSA. To understand the lack of cross resistance, clpC1 from spontaneously generated resistant clones from both leads were sequenced. This revealed several distinct single point mutations, suggesting these compounds bind differently to ClpC1. Checkerboard assay indicated a lack of antagonism between ECU and RUF-I and potential synergistic effects. Preliminary data indicates that ClpC1 could be a multifaceted drug target for multidrug resistant M. tuberculosis. Research pertaining to the peptide drug leads, associated analogues, and their mechanism of action against ClpC1 will be presented.