Tài liệu Báo cáo khoa học: Evolutionary divergence of valosin-containing protein ⁄cell division

Evolutionary divergence of valosin-containing protein⁄cell

division cycle protein 48 binding interactions among

endoplasmic reticulum-associated degradation proteins

Giacomo Morreale, Laura Conforti, John Coadwell, Anna L. Wilbrey and Michael P. Coleman

Laboratory of Molecular Signalling, The Babraham Institute, Cambridge, UK

Valosin-containing protein (VCP ⁄ p97) is an AAA￾ATPase associated with a variety of cellular activities,

most especially endoplasmic reticulum (ER)-associated

degradation (ERAD) [1], and its functional diversity

derives partly from its ability to bind a wide range of

protein cofactors [2]. Some bind directly to VCP in a

mutually exclusive manner, targeting VCP to a particu￾lar function. For example, binding to the ubiquitin

Keywords

endoplasmic reticulum-associated

degradation; Hrd1; Ube4b; ubiquitin ligase;

valosin-containing protein

Correspondence

G. Morreale, The Babraham Institute, B501,

Babraham Research Campus, Babraham,

Cambridge CB22 3AT, UK

Fax: +44 1223 496348

Tel: +44 1223 496251

E-mail: [email protected]

Centro di Ricerca per la Viticoltura, Via

Casoni, 13/A, 31058 Susegana (TV), Italy

Fax: +39-0438-738058

Tel: +39-0438-73264

E-mail: [email protected]

(Received 21 August 2008, revised 9

December 2008, accepted 16 December

2008)

doi:10.1111/j.1742-4658.2008.06858.x

Endoplasmic reticulum (ER)-associated degradation (ERAD) is a cell￾autonomous process that eliminates large quantities of misfolded, newly

synthesized protein, and is thus essential for the survival of any basic

eukaryotic cell. Accordingly, the proteins involved and their interaction

partners are well conserved from yeast to mammals, and Saccharomyces

cerevisiae is widely used as a model system with which to investigate this

fundamental cellular process. For example, valosin-containing protein

(VCP) and its yeast homologue cell division cycle protein 48 (Cdc48p),

which help to direct polyubiquitinated proteins for proteasome-mediated

degradation, interact with an equivalent group of ubiquitin ligases in

mouse and in S. cerevisiae. A conserved structural motif for cofactor bind￾ing would therefore be expected. We report a VCP-binding motif (VBM)

shared by mammalian ubiquitin ligase E4b (Ube4b)–ubiquitin fusion degra￾dation protein 2a (Ufd2a), hydroxymethylglutaryl reductase degradation

protein 1 (Hrd1)–synoviolin and ataxin 3, and a related sequence in

Mr 78 000 glycoprotein–Amfr with slightly different binding properties, and

show that Ube4b and Hrd1 compete for binding to the N-terminal domain

of VCP. Each of these proteins is involved in ERAD, but none has an

S. cerevisiae homologue containing the VBM. Some other invertebrate

model organisms also lack the VBM in one or more of these proteins, in con￾trast to vertebrates, where the VBM is widely conserved. Thus, consistent

with their importance in ERAD, evolution has developed at least two ways

to bring these proteins together with VCP–Cdc48p. However, the differing

molecular architecture of VCP–Cdc48p complexes indicates a key point of

divergence in the molecular details of ERAD mechanisms.

Abbreviations

Atx-3, ataxin 3; Cdc48p, cell division cycle protein 48; DAPI, 4¢,6-diamidino-2-phenylindole; EGFP, enhanced green fluorescent protein; ER,

endoplasmic reticulum; ERAD, endoplasmic reticulum-associated degradation; gp78, Mr 78 000 glycoprotein; GST, glutathione S-transferase;

Hrd1, hydroxymethylglutaryl reductase degradation protein 1; IBMPFD, inclusion body myopathy associated with Paget disease of bone and

frontotemporal dementia; OTUD7a, OUT domain-containing protein 7; SMURF, Smad ubiquitination regulatory factor; Ube4b, ubiquitin

ligase E4b; Ufd, ubiquitin fusion degradation protein; VBM, valosin-containing protein binding motif; VCP, valosin-containing protein;

WldS

, slow Wallerian degeneration protein.

1208 FEBS Journal 276 (2009) 1208–1220 ª 2009 The Authors Journal compilation ª 2009 FEBS