title: Non-proteolytic ubiquitylation counteracts the APC/C-inhibitory function of XErp1.
abstract: Mature Xenopus oocytes are arrested in meiosis by the activity of XErp1/Emi2, an inhibitor of the ubiquitin-ligase anaphase-promoting complex/cyclosome (APC/C). On fertilization, XErp1 is degraded, resulting in APC/C activation and the consequent degradation of cell-cycle regulators and exit from meiosis. In this study, we show that a modest increase in the activity of the ubiquitin-conjugating enzyme UbcX overrides the meiotic arrest in an APC/C-dependent reaction. Intriguingly, XErp1 remains stable in these conditions. We found that UbcX causes the ubiquitylation of XErp1, followed by its dissociation from the APC/C. Our data support the idea that ubiquitylation regulates the APC/C-inhibitory activity of XErp1.
authors.affiliation: Department of Molecular Genetics, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Hörmanseder
authors.forename: Thomas
authors.initials: T
authors.lastname: Tischer
authors.forename: Simone
authors.initials: S
authors.lastname: Heubes
authors.forename: Olaf
authors.initials: O
authors.lastname: Stemmann
authors.forename: Thomas U
authors.initials: TU
authors.lastname: Mayer
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D015153:Blotting, Western; D044783:F-Box Proteins / Q000378:metabolism*; D008540:Meiosis / Q000502:physiology*; D009865:Oocytes / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D043743:Ubiquitin-Protein Ligase Complexes / Q000037:antagonists & inhibitors*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination; D014981:Xenopus / Q000378:metabolism* / Q000502:physiology; D029867:Xenopus Proteins / Q000378:metabolism*
chemical_list: D044783:F-Box Proteins; C498166:FBXO43 protein, Xenopus; D029867:Xenopus Proteins; D043743:Ubiquitin-Protein Ligase Complexes; C513378:ube2c protein, Xenopus; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases