RT Journal Article
SR Electronic
T1 Ubiquitin- and ATP-dependent unfoldase activity of P97/VCP•NPLOC4•UFD1L1 is enhanced by a mutation that causes multisystem proteinopathy
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 129528
DO 10.1101/129528
A1 Emily E. Blythe
A1 Kristine C. Olson
A1 Vincent Chau
A1 Raymond J. Deshaies
YR 2017
UL http://biorxiv.org/content/early/2017/04/21/129528.abstract
AB p97 is a ‘segregase’ that plays a key role in numerous ubiquitin-dependent pathways, such as ER-associated degradation (ERAD). It has been hypothesized that p97 extracts proteins from membranes or macromolecular complexes to enable their proteasomal degradation; however, the complex nature of p97 substrates has made it difficult to directly observe the fundamental basis for this activity. To address this issue, we developed a soluble p97 substrate—Ub-GFP modified with K48-linked ubiquitin chains—for in vitro p97 activity assays. We demonstrate for the first time that wild type p97 can unfold proteins and that this activity is dependent on the p97 adaptor NPLOC4-UFD1L, ATP hydrolysis, and substrate ubiquitination, with branched chains providing maximal stimulation. Furthermore, we show that a p97 mutant that causes inclusion body myopathy, Paget’s Disease of bone, and frontotemporal dementia (IBMPFD) in humans unfolds substrate faster, suggesting that excess activity may underlie pathogenesis. This work overcomes a significant barrier in the study of p97 and will allow the future dissection of p97 mechanism at a level of detail previously unattainable.