2xeb

NMR STRUCTURE OF THE PROTEIN-UNBOUND SPLICEOSOMAL U4 SNRNA 5' STEM LOOP

spinqualitylabelsall models 2xeb Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xeb is a 2 chain structure with sequence from Homo sapiens. This structure supersedes the now removed PDB entry 2kr8. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed K-turn motifs are universal RNA structural elements providing a binding platform for proteins in several cellular contexts. Their characteristic is a sharp kink in the phosphate backbone that puts the two helical stems of the protein-bound RNA at an angle of 60 degrees . However, to date no high-resolution structure of a naked K-turn motif is available. Here, we present the first structural investigation at atomic resolution of an unbound K-turn RNA (the spliceosomal U4-Kt RNA) by a combination of NMR and small-angle neutron scattering data. With this study, we wish to address the question whether the K-turn structural motif assumes the sharply kinked conformation in the absence of protein binders and divalent cations. Previous studies have addressed this question by fluorescence resonance energy transfer, biochemical assays and molecular dynamics simulations, suggesting that the K-turn RNAs exist in equilibrium between a kinked conformation, which is competent for protein binding, and a more extended conformation, with the population distribution depending on the concentration of divalent cations. Our data shows that the U4-Kt RNA predominantly assumes the more extended conformation in the absence of proteins and divalent cations. The internal loop region is well structured but adopts a different conformation from the one observed in complex with proteins. Our data suggests that the K-turn consensus sequence does not per se code for the kinked conformation; instead the sharp backbone kink requires to be stabilized by protein binders. Structure of the K-turn U4 RNA: a combined NMR and SANS study.,Falb M, Amata I, Gabel F, Simon B, Carlomagno T Nucleic Acids Res. 2010 May 13. PMID:20466811 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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