5ona
From Proteopedia
Drosophila Bag-of-marbles CBM peptide bound to human CAF40-CNOT1
Structural highlights
Function[CNOT1_HUMAN] Belongs to the CCR4-NOT complex that functions as general transcription regulation complex. Acts as a transcriptional repressor. Represses the ligand-dependent transcriptional activation by nuclear receptors.[1] [2] [BAM_DROME] Required to initiate both male and female gametogenesis. May regulate cystoblast cell divisions.[3] [CNOT9_HUMAN] Component of the CCR4-NOT complex which is one of the major cellular mRNA deadenylases and is linked to various cellular processes including bulk mRNA degradation, miRNA-mediated repression, translational repression during translational initiation and general transcription regulation. Additional complex functions may be a consequence of its influence on mRNA expression. Involved in down-regulation of MYB- and JUN-dependent transcription. May play a role in cell differentiation (By similarity). Can bind oligonucleotides, such as poly-G, poly-C or poly-T (in vitro), but the physiological relevance of this is not certain. Does not bind poly-A. Enhances ligand-dependent transcriptional activity of nuclear hormone receptors, including RARA, expect ESR1-mediated transcription that is not only slightly increased, if at all.[4] [5] Publication Abstract from PubMedDrosophila melanogaster Bag-of-marbles (Bam) promotes germline stem cell (GSC) differentiation by repressing the expression of mRNAs encoding stem cell maintenance factors. Bam interacts with Benign gonial cell neoplasm (Bgcn) and the CCR4 deadenylase, a catalytic subunit of the CCR4-NOT complex. Bam has been proposed to bind CCR4 and displace it from the CCR4-NOT complex. Here, we investigated the interaction of Bam with the CCR4-NOT complex by using purified recombinant proteins. Unexpectedly, we found that Bam does not interact with CCR4 directly but instead binds to the CAF40 subunit of the complex in a manner mediated by a conserved N-terminal CAF40-binding motif (CBM). The crystal structure of the Bam CBM bound to CAF40 reveals that the CBM peptide adopts an alpha-helical conformation after binding to the concave surface of the crescent-shaped CAF40 protein. We further show that Bam-mediated mRNA decay and translational repression depend entirely on Bam's interaction with CAF40. Thus, Bam regulates the expression of its mRNA targets by recruiting the CCR4-NOT complex through interaction with CAF40. Drosophila Bag-of-marbles directly interacts with the CAF40 subunit of the CCR4-NOT complex to elicit repression of mRNA targets.,Sgromo A, Raisch T, Backhaus C, Keskeny C, Alva V, Weichenrieder O, Izaurralde E RNA. 2017 Dec 18. pii: rna.064584.117. doi: 10.1261/rna.064584.117. PMID:29255063[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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