title: Implications for the ubiquitination reaction of the anaphase-promoting complex from the crystal structure of the Doc1/Apc10 subunit.
abstract: The anaphase-promoting complex (APC) is a multi-subunit E3 protein ubiquitin ligase that is responsible for the metaphase to anaphase transition and the exit from mitosis. One of the subunits of the APC that is required for its ubiquitination activity is Doc1/Apc10, a protein composed of a Doc1 homology domain that has been identified in a number of diverse putative E3 ubiquitin ligases. Here, we present the crystal structure of Saccharomyces cerevisiae Doc1/Apc10 at 2.2A resolution. The Doc1 homology domain forms a beta-sandwich structure that is related in architecture to the galactose-binding domain of galactose oxidase, the coagulation factor C2 domain and a domain of XRCC1. Residues that are invariant amongst Doc1/Apc10 sequences, including a temperature-sensitive mitotic arrest mutant, map to a beta-sheet region of the molecule, whose counterpart in galactose oxidase, the coagulation factor C2 domains and XRCC1, mediate bio-molecular interactions. This finding suggests the identification of the functionally important and conserved region of Doc1/Apc10 and, since invariant residues of Doc1/Apc10 colocalise with conserved residues of other Doc1 homology domains, we propose that the Doc1 homology domains perform common ubiquitination functions in the APC and other E3 ubiquitin ligases.
authors.affiliation: Section of Structural Biology, Chester Beatty Laboratories, Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK.
authors.forename: Shannon W N
authors.initials: SW
authors.lastname: Au
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Leng
authors.forename: J Wade
authors.initials: JW
authors.lastname: Harper
authors.forename: David
authors.initials: D
authors.lastname: Barford
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D064197:Apc10 Subunit, Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D006801:Humans; D008025:Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013696:Temperature; D025801:Ubiquitin / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes
chemical_list: D064197:Apc10 Subunit, Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins; C577456:DOC1 protein, S cerevisiae; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D008025:Ligases