4b8c
nuclease module of the yeast Ccr4-Not complex
Structural highlights
FunctionPOP2_YEAST Acts as probably catalytic component of the CCR4-NOT core complex, which in the nucleus seems to be a general transcription factor, and in the cytoplasm the major mRNA deadenylase involved in mRNA turnover. In vitro, POP2 has 3'-exoribonuclease activity with a preference for poly(A) RNAs, but also degrades poly(U) and poly(C) RNAs. Is part of a glucose-sensing system involved in growth control in response to glucose availability.[1] [2] [3] [4] Publication Abstract from PubMedShortening eukaryotic poly(A) tails represses mRNA translation and induces mRNA turnover. The major cytoplasmic deadenylase, the Ccr4-Not complex, is a conserved multisubunit assembly. Ccr4-Not is organized around Not1, a large scaffold protein that recruits two 3'-5' exoribonucleases, Caf1 and Ccr4. We report structural studies showing that the N-terminal arm of yeast Not1 has a HEAT-repeat structure with domains related to the MIF4G fold. A MIF4G domain positioned centrally within the Not1 protein recognizes Caf1, which in turn binds the LRR domain of Ccr4 and tethers the Ccr4 nuclease domain. The interactions that form the nuclease core of the Ccr4-Not complex are evolutionarily conserved. Their specific disruption affects cell growth and mRNA deadenylation and decay in vivo in yeast. Thus, the N-terminal arm of Not1 forms an extended platform reminiscent of scaffolding proteins like eIF4G and CBP80, and places the two nucleases in a pivotal position within the Ccr4-Not complex. Architecture of the nuclease module of the yeast ccr4-not complex: the not1-caf1-ccr4 interaction.,Basquin J, Roudko VV, Rode M, Basquin C, Seraphin B, Conti E Mol Cell. 2012 Oct 26;48(2):207-18. doi: 10.1016/j.molcel.2012.08.014. Epub 2012 , Sep 6. PMID:22959269[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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