The Interplay of Cofactor Interactions and Post-translational Modifications in the Regulation of the AAA+ ATPase p97

Abstract

The hexameric type II AAA ATPase (ATPase associated with various activities) p97 (also referred to as VCP, Cdc48, and Ter94) is critically involved in a variety of cellular activities including pathways such as DNA replication and repair which both involve chromatin remodeling, and is a key player in various protein quality control pathways mediated by the ubiquitin proteasome system as well as autophagy. Correspondingly, p97 has been linked to various pathophysiological states including cancer, neurodegeneration, and premature aging. p97 encompasses an N-terminal domain, two highly conserved ATPase domains and an unstructured C-terminal tail. This enzyme hydrolyzes ATP and utilizes the resulting energy to extract or disassemble protein targets modified with ubiquitin from stable protein assemblies, chromatin and membranes. p97 participates in highly diverse cellular processes and hence its activity is tightly controlled. This is achieved by multiple regulatory cofactors, which either associate with the N-terminal domain or interact with the extreme C-terminus via distinct binding elements and target p97 to specific cellular pathways, sometimes requiring the simultaneous association with more than one cofactor. Most cofactors are recruited to p97 through conserved binding motifs/domains and assist in substrate recognition or processing by providing additional molecular properties. A tight control of p97 cofactor specificity and diversity as well as the assembly of higher-order p97-cofactor complexes is accomplished by various regulatory mechanisms, which include bipartite binding, binding site competition, changes in oligomeric assemblies, and nucleotide-induced conformational changes. Furthermore, post-translational modifications (PTMs) like acetylation, palmitoylation, phosphorylation, SUMOylation, and ubiquitylation of p97 have been reported which further modulate its diverse molecular activities. In this review, we will describe the molecular basis of p97-cofactor specificity/diversity and will discuss how PTMs can modulate p97-cofactor interactions and affect the physiological and patho-physiological functions of p97.

A Sensitive Yellow Fever Virus Entry Reporter Identifies Valosin-Containing Protein (VCP/p97) as an Essential Host Factor for Flavivirus Uncoating

“…It is worth noting that VCP/p97 has a weak affinity for ubiquitin and relies on a large array of cofactors, which typically encode enzymatic activities to facilitate VCP/p97 substrate processing, or adaptor molecules, which simply link VCP/ p97 to client substrates. Each of these adaptors and cofactors carry binding surfaces that recognize VCP/p97 and ubiquitin, respectively (81,82). Thus, VCP/p97 contributes to diverse cellular functions based this modular cofactor-and adaptor-mediated targeting strategy.…”

Valosin-containing protein VCP/p97 is essential for the intracellular development of Leishmania and its survival under heat stress

“…The functional diversity of VCP/p97 relies on its ability to associate with a large variety of regulatory cofactors which link VCP/p97 to a specific substrate in a subcellular compartment (adaptors) or recruit the substrates or mediate substrate processing (e.g., ubiquitin ligases, deubiquitinases, peptide N‐glycanases) and turnover (Buchberger, Schindelin, & Hänzelmann, ; Hänzelmann & Schindelin, ). To date, more than 40 cofactors have been identified in mammals from which the majority interacts via a small number of conserved binding modules.…”

Disparate peroxisome‐related defects in Arabidopsis pex6 and pex26 mutants link peroxisomal retrotranslocation and oil body utilization

“…The alignment shows the AAA 2 regions of Arabidopsis thaliana ( At ) and human ( Homo sapiens ; Hs ) PEX 6 and PEX 1 with human p97 highlighting the Walker A and B domains, arginine fingers (asterisks) and pex6 missense alleles. p97 pore loops 1 and 2 are underlined in gray, and pore loop 2 residues that are not ordered in the structure used to generate panel (f) (Hanzelmann and Schindelin, ) are in red. The alignment was generated using the Megalign program of DNAS tar using the Clustal W method.…”

“…Co‐crystallized ATP γS is in black. The illustration was generated using UCSF Chimera software (Pettersen et al ., ) from the p97 structure deposited as PDB ID 5C18 (Hanzelmann and Schindelin, ).…”