4u4c
From Proteopedia
The molecular architecture of the TRAMP complex reveals the organization and interplay of its two catalytic activities
Structural highlights
Function[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.[1] [AIR2_YEAST] Component of the TRAMP (TRF4) 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 like cryptic transcripts generated by RNA polymerase II and III, or hypomethylated pre-tRNAi-Met. Both complexes polyadenylate RNA processing and degradation intermediates of snRNAs, snoRNAs and mRNAs that accumulate in strains lacking a functional exosome. AIR2 also inhibits the methylation of NPL3 mediated by HMT1 through its interaction with HMT1.[2] [3] [4] [5] [6] Publication Abstract from PubMedThe TRAMP complex is involved in the nuclear surveillance and turnover of noncoding RNAs and intergenic transcripts. TRAMP is associated with the nuclear exosome and consists of a poly(A)polymerase subcomplex (Trf4-Air2) and a helicase (Mtr4). We found that N-terminal low-complexity regions of Trf4 and Air2 bind Mtr4 in a cooperative manner. The 2.4 A resolution crystal structure of the corresponding ternary complex reveals how Trf4 and Air2 wrap around the DExH core of the helicase. Structure-based mutations on the DExH core impair binding to Trf4 and Air2, and also to Trf5 and Air1. The combination of structural, biochemical, and biophysical data suggests that the poly(A)polymerase core of Trf4-Air2 is positioned below the base of the helicase, where the unwound 3' end of an RNA substrate is expected to emerge. The results reveal conceptual similarities between the two major regulators of the exosome, the nuclear TRAMP and cytoplasmic Ski complexes. The Molecular Architecture of the TRAMP Complex Reveals the Organization and Interplay of Its Two Catalytic Activities.,Falk S, Weir JR, Hentschel J, Reichelt P, Bonneau F, Conti E Mol Cell. 2014 Sep 18;55(6):856-67. doi: 10.1016/j.molcel.2014.07.020. Epub 2014 , Aug 28. PMID:25175027[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: RNA helicase | Bonneau, F | Conti, E | Falk, S | Hentschel, J | Reichelt, P | Weir, J R | Atpase | Exosome | Helicase | Hydrolase | Rna degradation
