Non-proteolytic ubiquitylation counteracts the APC/C-inhibitory function of XErp1

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Hormanseder, Eva ; Tischer, Thomas ; Heubes, Simone ; Stemmann, Olaf ; Mayer, Thomas U.:
Non-proteolytic ubiquitylation counteracts the APC/C-inhibitory function of XErp1.
In: EMBO Reports. Bd. 12 (12 Mai 2011) Heft 5 . - S. 436-443.
ISSN 1469-3178
DOI: https://doi.org/10.1038/embor.2011.32

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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.