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STRUCTURE OF A TWELVE COMPONENT MPP6-NUCLEAR RNA EXOSOME COMPLEX BOUND TO RNA
Structural highlights
FunctionRRP43_YEAST Non-catalytic component of the RNA exosome complex which has 3'->5' exoribonuclease activity and participates in a multitude of cellular RNA processing and degradation events. In the nucleus, the RNA exosome complex is involved in proper maturation of stable RNA species such as rRNA, snRNA and snoRNA, in the elimination of RNA processing by-products and non-coding 'pervasive' transcripts, such as antisense RNA species and cryptic unstable transcripts (CUTs), and of mRNAs with processing defects, thereby limiting or excluding their export to the cytoplasm. In the cytoplasm, the RNA exosome complex is involved in general mRNA turnover and in RNA surveillance pathways, preventing translation of aberrant mRNAs. The catalytic inactive RNA exosome core complex of 9 subunits (Exo-9) is proposed to play a pivotal role in the binding and presentation of RNA for ribonucleolysis, and to serve as a scaffold for the association with catalytic subunits and accessory proteins or complexes. RRP43 is part of the hexameric ring of RNase PH domain-containing subunits proposed to form a central channel which threads RNA substrates for degradation.[1] [2] [3] [4] Publication Abstract from PubMedNuclear RNA exosomes catalyze a range of RNA processing and decay activities that are coordinated in part by cofactors, including Mpp6, Rrp47, and the Mtr4 RNA helicase. Mpp6 interacts with the nine-subunit exosome core, while Rrp47 stabilizes the exoribonuclease Rrp6 and recruits Mtr4, but it is less clear if these cofactors work together. Using biochemistry with Saccharomyces cerevisiae proteins, we show that Rrp47 and Mpp6 stimulate exosome-mediated RNA decay, albeit with unique dependencies on elements within the nuclear exosome. Mpp6-exosomes can recruit Mtr4, while Mpp6 and Rrp47 each contribute to Mtr4-dependent RNA decay, with maximal Mtr4-dependent decay observed with both cofactors. The 3.3 A structure of a twelve-subunit nuclear Mpp6 exosome bound to RNA shows the central region of Mpp6 bound to the exosome core, positioning its Mtr4 recruitment domain next to Rrp6 and the exosome central channel. Genetic analysis reveals interactions that are largely consistent with our model. Structure and reconstitution of yeast Mpp6-nuclear exosome complexes reveals that Mpp6 stimulates RNA decay and recruits the Mtr4 helicase.,Wasmuth EV, Zinder JC, Zattas D, Das M, Lima CD Elife. 2017 Jul 25;6. pii: e29062. doi: 10.7554/eLife.29062. PMID:28742025[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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