Mechanistic studies of the ClpAP protease/

Abstract

CIpA, a member of the Hspl00/Clp subset of the AAA+ superfamily, is an energy-dependent chaperone, disassembling and remodeling its protein substrates. CIpA also serves as the ATPase component of the ClpAP protease, where it is resonsible for binding specific substrates and unfolding and translocating them into its partner ClpP, the proteolytic component of the complex. We have used single molecule and traditional biochemical experiments to probe the mechanism of the unfolding and translocation steps of ClpA's enzymatic activity. We have identified two states of varying substrate affinities and shown that the conformational switch between these states is responsible for protein translocation. We have also investigated ClpA's autounfolding activity and have demonstrated that though CIpA can disaggregate some substrates in vivo, it does not act as an autodisaggregase.