6akj
From Proteopedia
The crystal structure of EMC complex
Structural highlights
FunctionMMI1_SCHPO RNA-binding protein that recognizes and binds N6-methyladenosine (m6A)-containing RNAs, a modification present at internal sites of mRNAs and some non-coding RNAs (By similarity). Required for elemination of certain meiosis-specific mRNAs in an early event following transcription. May bind to the cis-acting region (DSR) of the mRNA, activating the nuclear exosome which may lead to the degradation of the transcript from the 3' region (PubMed:16823445).[UniProtKB:Q06390][1] ERH_SCHPO Forms part of the erh1-mmi1 complex that recruits the CCR4-NOT complex and the NURS complex to target RNAs (PubMed:26942678, PubMed:30651569, PubMed:31974447). Suppresses the meiotic program during vegetative growth and promotes the meiotic program during mating (PubMed:31974447). Recruitment of the NURS complex to target mRNAs promotes mRNA decay by engagement of the nuclear exosome, and formation of heterochromatin islands at meiotic genes silenced by the exosome (PubMed:26942678). Recruitment of the CCR4-NOT complex to target RNAs promotes heterochromatin formation at RNAi-dependent heterochromatin domains (HOODs), including a subset of meiotic genes, lncRNAs and retrotransposons (PubMed:26942678). Recruitment of the CCR4-NOT complex to rDNA promotes rDNA heterochromatin assembly (PubMed:26942678).[2] [3] [4] Publication Abstract from PubMedGene regulatory mechanisms rely on a complex network of RNA processing factors to prevent untimely gene expression. In fission yeast, the highly conserved ortholog of human ERH, called Erh1, interacts with the YTH family RNA binding protein Mmi1 to form the Erh1-Mmi1 complex (EMC) implicated in gametogenic gene silencing. However, the structural basis of EMC assembly and its functions are poorly understood. Here, we present the co-crystal structure of the EMC that consists of Erh1 homodimers interacting with Mmi1 in a 2:2 stoichiometry via a conserved molecular interface. Structure-guided mutation of the Mmi1(Trp112) residue, which is required for Erh1 binding, causes defects in facultative heterochromatin assembly and gene silencing while leaving Mmi1-mediated transcription termination intact. Indeed, EMC targets masked in mmi1 due to termination defects are revealed in mmi1(W112A). Our study delineates EMC requirements in gene silencing and identifies an ERH interface required for interaction with an RNA binding protein. A conserved dimer interface connects ERH and YTH family proteins to promote gene silencing.,Xie G, Vo TV, Thillainadesan G, Holla S, Zhang B, Jiang Y, Lv M, Xu Z, Wang C, Balachandran V, Shi Y, Li F, Grewal SIS Nat Commun. 2019 Jan 16;10(1):251. doi: 10.1038/s41467-018-08273-9. PMID:30651569[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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