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Structure of the Rrp6-Rrp47-Mtr4 interactionStructure of the Rrp6-Rrp47-Mtr4 interaction
Structural highlights
Function[RRP6_YEAST] Nuclear-specific 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. 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. RRP6 has 3'-5' exonuclease activity which is not modulated upon association with Exo-9 suggesting that the complex inner RNA-binding path is not used to access its active site.[1] [2] [3] [4] [MTR4_YEAST] ATP-dependent RNA helicase required for the 3'-end formation of 5.8S RNA. Cofactor for the exosome complex that unwinds secondary structure in pre-rRNA. Required for nucleocytoplasmic transport of mRNA. May serve as a chaperone which translocates or normalizes the structure of mRNAs in preparation for export. Component of the TRAMP complex which has a poly(A) RNA polymerase activity and is involved in a post-transcriptional quality control mechanism limiting inappropriate expression of genetic information. Polyadenylation is required for the degradative activity of the exosome on several of its nuclear RNA substrates.[5] [LRP1_YEAST] Required for exosome-dependent processing of pre-rRNA and small nucleolar RNA (snRNA) precursors. Involved in processing of 35S pre-rRNA at the A0, A1 and A2 sites. Required for activity of RRP6 in 7S pre-rRNA processing. Also has a role in 3'-processing of U4 and U5 small nuclear RNAs (snRNAs). Acts as a mRNA export factor. Mediates mRNA degradation upon UV irradiation. Maintains genome integrity where it is involved in both non-homologous end joining (NHEJ) and homologous recombination pathway repair of double strand DNA breaks. During NHEJ, required for joining 3'-overhanging ends. Also involved in telomere length regulation and maintenance.[6] [7] [8] [9] [10] Publication Abstract from PubMedThe exosome is a conserved multi-subunit ribonuclease complex that functions in 3' end processing, turnover and surveillance of nuclear and cytoplasmic RNAs. In the yeast nucleus, the 10-subunit core complex of the exosome (Exo-10) physically and functionally interacts with the Rrp6 exoribonuclease and its associated cofactor Rrp47, the helicase Mtr4 and Mpp6. Here, we show that binding of Mtr4 to Exo-10 in vitro is dependent upon both Rrp6 and Rrp47, whereas Mpp6 binds directly and independently of other cofactors. Crystallographic analyses reveal that the N-terminal domains of Rrp6 and Rrp47 form a highly intertwined structural unit. Rrp6 and Rrp47 synergize to create a composite and conserved surface groove that binds the N-terminus of Mtr4. Mutation of conserved residues within Rrp6 and Mtr4 at the structural interface disrupts their interaction and inhibits growth of strains expressing a C-terminal GFP fusion of Mtr4. These studies provide detailed structural insight into the interaction between the Rrp6-Rrp47 complex and Mtr4, revealing an important link between Mtr4 and the core exosome. The exosome-binding factors Rrp6 and Rrp47 form a composite surface for recruiting the Mtr4 helicase.,Schuch B, Feigenbutz M, Makino DL, Falk S, Basquin C, Mitchell P, Conti E EMBO J. 2014 Oct 15. pii: e201488757. PMID:25319414[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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