Identification of a ubiquitin-protein ligase subunit within the CCR4-NOT transcription repressor complex

EMBO J. 2002 Feb 1;21(3):355-64. doi: 10.1093/emboj/21.3.355.

Abstract

The RING finger protein CNOT4 is a component of the CCR4-NOT complex. This complex is implicated in repression of RNA polymerase II transcription. Here we demonstrate that CNOT4 functions as a ubiquitin-protein ligase (E3). We show that the unique C4C4 RING domain of CNOT4 interacts with a subset of ubiquitin-conjugating enzymes (E2s). Using NMR spectroscopy, we detail the interaction of CNOT4 with UbcH5B and characterize RING residues that are critical for this interaction. CNOT4 acts as a potent E3 ligase in vitro. Mutations that destabilize the E2-E3 interface abolish this activity. Based on these results, we present a model of how E3 ligase function within the CCR4-NOT complex relates to transcriptional regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • DNA-Binding Proteins / genetics
  • Fungal Proteins / genetics*
  • Ligases / genetics*
  • Models, Molecular
  • Molecular Sequence Data
  • Repressor Proteins / genetics*
  • Ribonucleases*
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors / genetics*
  • Transcription, Genetic
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases

Substances

  • DNA-Binding Proteins
  • Fungal Proteins
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases
  • CCR4 protein, S cerevisiae
  • Ribonucleases
  • Ligases