title: Structure and function of a HECT domain ubiquitin-binding site.
abstract: The Rsp5 ubiquitin ligase contains a non-covalent binding site for ubiquitin within the amino-terminal lobe (N-lobe) of the HECT domain, and the X-ray crystal structure of the HECT-ubiquitin complex has been determined. Hydrophobic patch residues of ubiquitin (L8, I44, V70) were crucial for interaction with Rsp5, and amino-acid alterations at the Rsp5-binding interface resulted in defects in polyubiquitination. Our results support a model in which the N-lobe-binding site acts to localize and orient the distal end of the ubiquitin chain to promote conjugation of the next ubiquitin molecule.
authors.affiliation: Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA.
authors.forename: Hyung Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Alanna M
authors.initials: AM
authors.lastname: Steffen
authors.forename: Michael L
authors.initials: ML
authors.lastname: Oldham
authors.forename: Jue
authors.initials: J
authors.lastname: Chen
authors.forename: Jon M
authors.initials: JM
authors.lastname: Huibregtse
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D043743:Ubiquitin-Protein Ligase Complexes; C469287:RSP5 protein, S cerevisiae