Furthering the understanding of MtbClpS regulation of MtbClpC1 as it relates to structure and function

Abstract

Mycobacterium tuberculosis (Mtb) has developed significant drug-resistance in recent years, thereby necessitating novel drug targets for pathogenic bacteria. The AAA+ (ATPase Associated with various cellular Activities) chaperone of MtbClpC1 could serve as a target for drug development due to its critical role in the maintenance of protein homeostasis. MtbClpC1 hexamers couple the energy of ATP hydrolysis to unfold and translocate protein substrates into an associated MtbClpP protease. The substrate specificity of these unfoldases is regulated by the ATPase component and potential adaptor protein association. No adaptor protein-mediated control has been reported for MtbClpC1. Using in vitro and in silico methods, we report data demonstrating that MtbClpC1 catalyzed unfolding of SsrA-tagged protein is negatively impacted by MtbClpS association. This does not require the expected ClpC1 N-terminal domain (NTD), but instead requires the presence of an interaction located in the Middle Domain (MD).