title: Structure of a RING E3 ligase and ubiquitin-loaded E2 primed for catalysis.
abstract: Ubiquitin modification is mediated by a large family of specificity determining ubiquitin E3 ligases. To facilitate ubiquitin transfer, RING E3 ligases bind both substrate and a ubiquitin E2 conjugating enzyme linked to ubiquitin via a thioester bond, but the mechanism of transfer has remained elusive. Here we report the crystal structure of the dimeric RING domain of rat RNF4 in complex with E2 (UbcH5A) linked by an isopeptide bond to ubiquitin. While the E2 contacts a single protomer of the RING, ubiquitin is folded back onto the E2 by contacts from both RING protomers. The carboxy-terminal tail of ubiquitin is locked into an active site groove on the E2 by an intricate network of interactions, resulting in changes at the E2 active site. This arrangement is primed for catalysis as it can deprotonate the incoming substrate lysine residue and stabilize the consequent tetrahedral transition-state intermediate.
authors: Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors: Anna
authors: A
authors: Plechanovová
authors: Ellis G
authors: EG
authors: Jaffray
authors: Michael H
authors: MH
authors: Tatham
authors: James H
authors: JH
authors: Naismith
authors: Ronald T
authors: RT
authors: Hay
mesh_terms: D000818:Animals; D055162:Biocatalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism; D054875:Ubiquitination; D016335:Zinc Fingers
chemical_list: D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D014157:Transcription Factors; D025801:Ubiquitin; C097308:UBE2D1 protein, human; D044763:Ubiquitin-Conjugating Enzymes; C486411:Rnf4 protein, rat; D044767:Ubiquitin-Protein Ligases