2vnu
From Proteopedia
Crystal structure of Sc Rrp44
Structural highlights
Function[RRP44_YEAST] 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. DIS3 has both 3'-5' exonuclease and endonuclease activities. The exonuclease activity of DIS3 is down-regulated upon association with Exo-9 possibly involving a conformational change in the catalytic domain and threading of the RNA substrate through the complex central channel. Structured substrates can be degraded if they have a 3' single-stranded extension sufficiently long (such as 35 nt poly(A)) to span the proposed complex inner RNA-binding path and to reach the exonuclease site provided by DIS3. Plays a role in mitotic control.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe eukaryotic exosome is a macromolecular complex essential for RNA processing and decay. It has recently been shown that the RNase activity of the yeast exosome core can be mapped to a single subunit, Rrp44, which processively degrades single-stranded RNAs as well as RNAs containing secondary structures. Here we present the 2.3 A resolution crystal structure of S. cerevisiae Rrp44 in complex with single-stranded RNA. Although Rrp44 has a linear domain organization similar to bacterial RNase II, in three dimensions the domains have a different arrangement. The three domains of the classical nucleic-acid-binding OB fold are positioned on the catalytic domain such that the RNA-binding path observed in RNase II is occluded. Instead, RNA is threaded to the catalytic site via an alternative route suggesting a mechanism for RNA-duplex unwinding. The structure provides a molecular rationale for the observed biochemical properties of the RNase R family of nucleases. Structure of the active subunit of the yeast exosome core, Rrp44: diverse modes of substrate recruitment in the RNase II nuclease family.,Lorentzen E, Basquin J, Tomecki R, Dziembowski A, Conti E Mol Cell. 2008 Mar 28;29(6):717-28. PMID:18374646[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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