A major conformational change in p97 AAA ATPase upon ATP binding

AAA ATPases play central roles in cellular activities. The ATPase p97, a pr ototype of this superfamily, participates in organelle membrane fusion. Cry oelectron microscopy and single-particle analysis revealed that a major con formational change of p97 during the ATPase cycle occurred upon nucleotide binding and not during hydrolysis as previously hypothesized. Furthermore, our study indicates that six p47 adaptor molecules bind to the periphery of the ring-shaped p97 hexamer. Taken together, these results provide a revis ed model of how this and possibly other AAA ATPases can translate nucleotid e binding into conformational changes of associated binding partners.