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The Structure of a Class II ubiquitin-conjugating enzyme, Ubc1.
Structural highlights
FunctionUBC1_YEAST Catalyzes the covalent attachment of ubiquitin to other proteins. Functions in degradation of misfolded or regulated proteins localized in the endoplasmic reticulum (ER) lumen or membrane via the ubiquitin-proteasome system. Cognate E2 conjugating enzyme for the HRD1 ubiquitin ligase complex, which is part of the ERAD-L and ERAD-M pathways responsible for the rapid degradation of soluble lumenal and membrane proteins with misfolded lumenal domains (ERAD-L), or ER-membrane proteins with misfolded transmembrane domains (ERAD-M).[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedE2 conjugating enzymes form a thiol ester intermediate with ubiquitin, which is subsequently transferred to a substrate protein targeted for degradation. While all E2 proteins comprise a catalytic domain where the thiol ester is formed, several E2s (class II) have C-terminal extensions proposed to control substrate recognition, dimerization, or polyubiquitin chain formation. Here we present the novel solution structure of the class II E2 conjugating enzyme Ubc1 from Saccharomyces cerevisiae. The structure shows the N-terminal catalytic domain adopts an alpha/beta fold typical of other E2 proteins. This domain is physically separated from its C-terminal domain by a 22-residue flexible tether. The C-terminal domain adopts a three-helix bundle that we have identified as an ubiquitin-associated domain (UBA). NMR chemical shift perturbation experiments show this UBA domain interacts in a regioselective manner with ubiquitin. This two-domain structure of Ubc1 was used to identify other UBA-containing class II E2 proteins, including human E2-25K, that likely have a similar architecture and to determine the role of the UBA domain in facilitating polyubiquitin chain formation. Solution structure of the flexible class II ubiquitin-conjugating enzyme Ubc1 provides insights for polyubiquitin chain assembly.,Merkley N, Shaw GS J Biol Chem. 2004 Nov 5;279(45):47139-47. Epub 2004 Aug 24. PMID:15328341[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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