2o32

Solution structure of U2 snRNA stem I from human, containing modified nucleotides

spinqualitylabelsall models 2o32, 20 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2o32 is a 1 chain structure. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: OMG, PSU Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The spliceosome is a dynamic ribonucleoprotein complex responsible for the removal of intron sequences from pre-messenger RNA. The highly conserved 5' end of the U2 small nuclear RNA (snRNA) makes key base-pairing interactions with the intron branch point sequence and U6 snRNA. U2 stem I, a stem-loop located in the 5' region of U2, has been implicated in spliceosome assembly and may modulate the folding of the U2 and U6 snRNAs in the spliceosome active site. Here we present the NMR structures of U2 stem I from human and Saccharomyces cerevisiae. These sequences represent the two major classes of U2 stem I, distinguished by the identity of tandem wobble pairs (UU/UU in yeast and CA/GU in human) and the presence of post-transcriptional modifications (four 2'-O-methyl groups and two pseudouracils in human). The structures reveal that the UU/UU and CA/GU tandem wobble pairs are nearly isosteric. The tandem wobble pairs separate two thermodynamically distinct regions of Watson-Crick base pairs, with the modified nucleotides in human stem I conferring a significant increase in stability. We hypothesize that the separate thermodynamic stabilities of U2 stem I exist to allow the structure to transition through different folded conformations during spliceosome assembly and catalysis. Structure and thermodynamics of a conserved U2 snRNA domain from yeast and human.,Sashital DG, Venditti V, Angers CG, Cornilescu G, Butcher SE RNA. 2007 Mar;13(3):328-38. Epub 2007 Jan 22. PMID:17242306 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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