Budding Yeast RSI1/APC2, a Novel Gene Necessary for Initiation of Anaphase, Encodes an APC Subunit

EMBO J. 1998 Jan 15;17(2):498-506. doi: 10.1093/emboj/17.2.498.

Abstract

SIC1 is a non-essential gene encoding a CDK inhibitor of Cdc28-Clb kinase activity. Sic1p is involved in both mitotic exit and the timing of DNA synthesis. To identify other genes involved in controlling Clb-kinase activity, we have undertaken a genetic screen for mutations which render SIC1 essential. Here we describe a gene we have identified by this means, RSI1/APC2. Temperature-sensitive rsi1/apc2 mutants arrest in metaphase and are unable to degrade Clb2p, suggesting that Rsi1p/Apc2p is associated with the anaphase promoting complex (APC). This is an E3 ubiquitin-ligase that controls anaphase initiation through degradation of Pds1p and mitotic exit via degradation of Clb cyclins. Indeed, the anaphase block in rsi1/apc2 temperature-sensitive mutants is overcome by removal of PDS1, consistent with Rsi1p/Apc2p being part of the APC. In addition, like our rsi1/apc2 mutations, cdc23-1, encoding a known APC subunit, is also lethal with sic1Delta. Thus SIC1 clearly becomes essential when APC function is compromised. Finally, we find that Rsi1p/Apc2p co-immunoprecipitates with Cdc23p. Taken together, our results suggest that RSI1/APC2 is a subunit of APC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anaphase / genetics*
  • Anaphase-Promoting Complex-Cyclosome
  • Apc2 Subunit, Anaphase-Promoting Complex-Cyclosome
  • Apc8 Subunit, Anaphase-Promoting Complex-Cyclosome
  • Cell Cycle Proteins / genetics*
  • Cyclin B*
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • Cyclins / deficiency
  • Cyclins / metabolism
  • Cyclins / physiology
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Fungal Proteins / physiology
  • Genes, Fungal*
  • Genes, Lethal
  • Ligases / genetics*
  • Molecular Sequence Data
  • Mutagenesis
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Phenotype
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / isolation & purification
  • Saccharomyces cerevisiae Proteins*
  • Securin
  • Temperature
  • Ubiquitin-Protein Ligase Complexes*
  • Ubiquitin-Protein Ligases

Substances

  • Apc8 Subunit, Anaphase-Promoting Complex-Cyclosome
  • CDC23 protein, S cerevisiae
  • CLB2 protein, S cerevisiae
  • Cell Cycle Proteins
  • Cyclin B
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • Cyclins
  • Fungal Proteins
  • Nuclear Proteins
  • PDS1 protein, S cerevisiae
  • SIC1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Securin
  • Ubiquitin-Protein Ligase Complexes
  • APC2 protein, S cerevisiae
  • Anaphase-Promoting Complex-Cyclosome
  • Apc2 Subunit, Anaphase-Promoting Complex-Cyclosome
  • Ubiquitin-Protein Ligases
  • Ligases