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Measuring In Vitro ATPase Activity for Enzymatic Characterization
Published on: August 23, 2016
High-speed atomic force microscopic observation of ATP-dependent rotation of the AAA+ chaperone p97
Kentaro Noi1, Daisuke Yamamoto, Shingo Nishikori
1Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan; The Global COE (Cell Fate Regulation Research and Education Unit), Kumamoto University, Kumamoto 860-0811, Japan.
Abstract:
p97 (also called VCP and CDC-48) is an AAA+ chaperone, which consists of a substrate/cofactor-binding N domain and two ATPase domains (D1 and D2), and forms a homo-hexameric ring. p97 plays crucial roles in a variety of cellular processes such as the ubiquitin-proteasome pathway, the endoplasmic reticulum-associated protein degradation, autophagy, and modulation of protein aggregates. Mutations in human p97 homolog VCP are linked to neurodegenerative diseases. The key mechanism of p97 in these various functions has been proposed to be the disassembly of protein complexes. To understand the molecular mechanism of p97, we studied the conformational changes of hexameric CDC-48.1, a Caenorhabditis elegans p97 homolog, using high-speed atomic force microscopy. In the presence of ATP, the N-D1 ring repeatedly rotates ~23 ± 8° clockwise and resets relative to the D2 ring. Mutational analysis reveals that this rotation is induced by ATP binding to the D2 domain.
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