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Interaction between the AAA+ ATPase p97 and its cofactor ataxin3 in health and disease: Nucleotide-induced conformational changes regulate cofactor binding
Journal article   Open access   Peer reviewed

Interaction between the AAA+ ATPase p97 and its cofactor ataxin3 in health and disease: Nucleotide-induced conformational changes regulate cofactor binding

Maya V. Rao, Dewight R. Williams, Simon Cocklin and Patrick J. Loll
The Journal of biological chemistry, v 292(45), pp 18392-18407
22 Sep 2017
PMID: 28939772
url
https://doi.org/10.1074/jbc.M117.806281View
Published, Version of Record (VoR)CC BY V4.0 Open

Abstract

ataxin3 ATPases associated with diverse cellular activities (AAA) cofactor binding conformational change electron microscopy (EM) Molecular Bases of Disease multisystem proteinopathy 1 (MSP1) nucleotide regulation p97 proteostasis surface plasmon resonance (SPR) VCP
p97 is an essential ATPase associated with various cellular activities (AAA + ) that functions as a segregase in diverse cellular processes, including the maintenance of proteostasis. p97 interacts with different cofactors that target it to distinct pathways; an important example is the deubiquitinase ataxin3, which collaborates with p97 in endoplasmic reticulum-associated degradation. However, the molecular details of this interaction have been unclear. Here, we characterized the binding of ataxin3 to p97, showing that ataxin3 binds with low-micromolar affinity to both wild-type p97 and mutants linked to degenerative disorders known as multisystem proteinopathy 1 (MSP1); we further showed that the stoichiometry of binding is one ataxin3 molecule per p97 hexamer. We mapped the binding determinants on each protein, demonstrating that ataxin3's p97/VCP-binding motif interacts with the inter-lobe cleft in the N-domain of p97. We also probed the nucleotide dependence of this interaction, confirming that ataxin3 and p97 associate in the presence of ATP and in the absence of nucleotide, but not in the presence of ADP. Our experiments suggest that an ADP-driven downward movement of the p97 N-terminal domain dislodges ataxin3 by inducing a steric clash between the D1-domain and ataxin3's C terminus. In contrast, MSP1 mutants of p97 bind ataxin3 irrespective of their nucleotide state, indicating a failure by these mutants to translate ADP binding into a movement of the N-terminal domain. Our model provides a mechanistic explanation for how nucleotides regulate the p97–ataxin3 interaction and why atypical cofactor binding is observed with MSP1 mutants.

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Collaboration types
Domestic collaboration
Web of Science research areas
Biochemistry & Molecular Biology
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