Invited Review ATP-Driven Molecular Chaperone Machines

This review is focused on the mechanisms by which ATP bind-ing and hydrolysis drive chaperone machines assisting protein folding and unfolding. A survey of the key, general chaperone systems Hsp70 and Hsp90, and the unfoldase Hsp100 is fol-lowed by a focus on the Hsp60 chaperonin machine which is understood in most detail. Cryo-electron microscopy analysis of the E. coli Hsp60 GroEL reveals intermediate conforma-tions in the ATPase cycle and in substrate folding. These struc-tures suggest a mechanism by which GroEL can forcefully unfold and then encapsulate substrates for subsequent folding in isolation from all other binding surfaces.VC 2013 Wile