A role for the Fizzy/Cdc20 family of proteins in activation of the APC/C distinct from substrate recruitment

Mol Cell. 2008 Nov 21;32(4):576-83. doi: 10.1016/j.molcel.2008.09.023.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaphase-Promoting Complex-Cyclosome
  • Animals
  • Cdc20 Proteins
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Models, Biological
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / metabolism
  • Proteins / genetics
  • Proteins / metabolism*
  • Substrate Specificity
  • Ubiquitin-Protein Ligase Complexes / metabolism*
  • Ubiquitination
  • Xenopus / genetics
  • Xenopus / metabolism
  • Xenopus Proteins / chemistry
  • Xenopus Proteins / genetics
  • Xenopus Proteins / metabolism*

Substances

  • Cdc20 Proteins
  • Cdc20 protein, Xenopus
  • Cell Cycle Proteins
  • Proteins
  • Xenopus Proteins
  • Ubiquitin-Protein Ligase Complexes
  • Anaphase-Promoting Complex-Cyclosome
  • NEK2 protein, Xenopus
  • Protein-Serine-Threonine Kinases