5k36
Structure of an eleven component nuclear RNA exosome complex bound to RNA
Structural highlights
FunctionRRP45_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. RRP45 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] Publication Abstract from PubMedThe eukaryotic RNA exosome is an essential and conserved 3'-to-5' exoribonuclease complex that degrades or processes nearly every class of cellular RNA. The nuclear RNA exosome includes a 9-subunit non-catalytic core that binds Rrp44 (Dis3) and Rrp6 subunits to modulate their processive and distributive 3'-to-5' exoribonuclease activities, respectively. Here we utilize an engineered RNA with two 3' ends to obtain a crystal structure of an 11-subunit nuclear exosome bound to RNA at 3.1 A. The structure reveals an extended RNA path to Rrp6 that penetrates into the non-catalytic core; contacts between the non-catalytic core and Rrp44, which inhibit exoribonuclease activity; and features of the Rrp44 exoribonuclease site that support its ability to degrade 3' phosphate RNA substrates. Using reconstituted exosome complexes, we show that 3' phosphate RNA is not a substrate for Rrp6 but is readily degraded by Rrp44 in the nuclear exosome. Nuclear RNA Exosome at 3.1 A Reveals Substrate Specificities, RNA Paths, and Allosteric Inhibition of Rrp44/Dis3.,Zinder JC, Wasmuth EV, Lima CD Mol Cell. 2016 Nov 17;64(4):734-745. doi: 10.1016/j.molcel.2016.09.038. Epub 2016, Nov 3. PMID:27818140[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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