Identification of a ubiquitin-protein ligase subunit within the CCR4-NOT transcription repressor complex.
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.
Albert
Thomas K
TK
Laboratory for Physiological Chemistry, University Medical Center, 3508 AB Utrecht, The Netherlands.
Hanzawa
Hiroyuki
H
Legtenberg
Yvonne I A
YI
de Ruwe
Marjolein J
MJ
van den Heuvel
Fiona A J
FA
Collart
Martine A
MA
Boelens
Rolf
R
Timmers
H Th Marc
HT
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D008025:Ligases / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000235:genetics*; D012260:Ribonucleases; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; C078657:CCR4 protein, S cerevisiae; D012260:Ribonucleases; D008025:Ligases