Emi2 mediates meiotic MII arrest by competitively inhibiting the binding of Ube2S to the APC/C

Kosuke Sako, Kazuhiro Suzuki, Michitaka Isoda, Satomi Yoshikai, Chiharu Senoo, Nobushige Nakajo, Munemichi Ohe, Noriyuki Sagata

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

In vertebrates, unfertilized eggs are arrested at metaphase of meiosis II by Emi2, a direct inhibitor of the APC/C ubiquitin ligase. Two different ubiquitin-conjugating enzymes, UbcH10 and Ube2S, work with the APC/C to target APC/C substrates for degradation. However, their possible roles and regulations in unfertilized/fertilized eggs are not known. Here we use Xenopus egg extracts to show that both UbcH10 and Ube2S are required for rapid cyclin B degradation at fertilization, when APC/C binding of Ube2S, but not of UbcH10, increases several fold, coincidently with (SCFβ-TrCP-dependent) Emi2 degradation. Interestingly, before fertilization, Emi2 directly inhibits APC/C-Ube2S binding via the C-terminal tail, but on fertilization, its degradation allows the binding mediated by the Ube2S C-terminal tail. Significantly, Emi2 and Ube2S bind commonly to the APC/C catalytic subunit APC10 via their similar C-terminal tails. Thus, Emi2 competitively inhibits APC/C-Ube2S binding before fertilization, while its degradation on fertilization relieves the inhibition for APC/C activation.

Original languageEnglish
Article number3667
JournalNature communications
Volume5
DOIs
Publication statusPublished - Apr 28 2014

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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