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[Report] 2.3 Å resolution cryo-EM structure of human p97 and mechanism of allosteric inhibition

ScienceNOW - Fetched: February 18th, 2016, 3:00pm UTC

p97 is a hexameric AAA+ adenosine triphosphatase (ATPase) that is an attractive target for cancer drug development. We report cryo–electron microscopy (cryo-EM) structures for adenosine diphosphate (ADP)–bound, full-length, hexameric wild-type p97 in the presence and absence of an allosteric inhibitor at resolutions of 2.3 and 2.4 angstroms, respectively. We also report cryo-EM structures (at resolutions of ~3.3, 3.2, and 3.3 angstroms, respectively) for three distinct, coexisting functional states of p97 with occupancies of zero, one, or two molecules of adenosine 5′-O-(3-thiotriphosphate) (ATPγS) per protomer. A large corkscrew-like change in molecular architecture, coupled with upward displacement of the N-terminal domain, is observed only when ATPγS is bound to both the D1 and D2 domains of the protomer. These cryo-EM structures establish the sequence of nucleotide-driven structural changes in p97 at atomic resolution. They also enable elucidation of the binding mode of an allosteric small-molecule inhibitor to p97 and illustrate how inhibitor binding at the interface between the D1 and D2 domains prevents propagation of the conformational changes necessary for p97 function. Authors: Soojay Banerjee, Alberto Bartesaghi, Alan Merk, Prashant Rao, Stacie L. Bulfer, Yongzhao Yan, Neal Green, Barbara Mroczkowski, R. Jeffrey Neitz, Peter Wipf, Veronica Falconieri, Raymond J. Deshaies, Jacqueline L. S. Milne, Donna Huryn, Michelle Arkin, Sriram Subramaniam

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