4b8c
From Proteopedia
nuclease module of the yeast Ccr4-Not complex
Structural highlights
Function[POP2_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] [CCR4_YEAST] Acts as 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. CCR4 has 3'-5' RNase activity with a strong preference for polyadenylated substrates and also low exonuclease activity towards single-stranded DNA. Discovered because of its role in the control of ADH2 gene expression. It is required for the expression of genes involved in non-fermentative growth and it mediates or is required for the action of the SPT6 and SPT10 genes.[5] [6] [7] [8] [NOT1_YEAST] Acts as 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. The NOT protein subcomplex negatively regulates the basal and activated transcription of many genes. Preferentially affects TC-type TATA element-dependent transcription. Could directly or indirectly inhibit component(s) of the general transcription machinery.[9] 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[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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