title: A role for the Fizzy/Cdc20 family of proteins in activation of the APC/C distinct from substrate recruitment.
abstract: The Fizzy/Cdc20 family of proteins are essential activators of the anaphase-promoting complex/cyclosome (APC/C), a multisubunit E3 ubiquitin ligase. However, apart from the well-established role of the C-terminal WD40 domain in substrate recognition, the precise roles of the activators remain elusive. Here we show that Nek2A, which directly binds the APC/C, can be ubiquitylated and destroyed in Fizzy/Cdc20-depleted Xenopus egg extracts when only the N-terminal domain of Fizzy/Cdc20 (N-Cdc20) is added. This activity is dependent upon the C box and is conserved in the alternative activator, Fizzy-related/Cdh1. In contrast, canonical substrates such as cyclin B and securin require both the N-terminal and WD40 domains, unless N-Cdc20 is fused to substrates when the WD40 domain becomes dispensable. Furthermore, in Cdc20-depleted cells, N-Cdc20 can facilitate Nek2A destruction in a C box-dependent manner. Our results reveal a role for the N-terminal domain of the Fizzy/Cdc20 family of activators in triggering substrate ubiquitylation by the APC/C.
authors.affiliation: Cell Cycle Control Laboratory, Marie Curie Research Institute, The Chart, Oxted, RH8 0TL Surrey, UK.
authors.forename: Yuu
authors.initials: Y
authors.lastname: Kimata
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Baxter
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Fry
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamano
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*; D054875:Ubiquitination; D014981:Xenopus / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D064199:Cdc20 Proteins; C577501:Cdc20 protein, Xenopus; D018797:Cell Cycle Proteins; D011506:Proteins; D029867:Xenopus Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; C490316:NEK2 protein, Xenopus; D017346:Protein Serine-Threonine Kinases