1i3x

SOLUTION STRUCTURE OF THE A LOOP OF 23S RIBOSOMAL RNA

spinqualitylabelsall models 1i3x, 15 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1i3x is a 1 chain structure. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 1i3y Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The A loop is an essential RNA component of the ribosome peptidyltransferase center that directly interacts with aminoacyl (A)-site tRNA. The A loop is highly conserved and contains a ubiquitous 2'-O-methyl ribose modification at position U2552. Here, we present the solution structure of a modified and unmodified A-loop RNA to define both the A-loop fold and the structural impact of the U2552 modification. Solution data reveal that the A-loop RNA has a compact structure that includes a noncanonical base pair between C2556 and U2552. NMR evidence is presented that the N3 position of C2556 has a shifted pKa and that protonation at C2556-N3 changes the C-U pair geometry. Our data indicate that U2552 methylation modifies the A-loop fold, in particular the dynamics and position of residues C2556 and U2555. We compare our structural data with the structure of the A loop observed in a recent 50S crystal structure [Ban, N., Nissen, P., Hansen, J., Moore, P. B. & Steitz, T. A. (2000) Science 289, 905--920; Nissen, P., Hansen, J., Ban, N., Moore, P. B. & Steitz, T. A. (2000) Science 289, 920--930]. The solution and crystal structures of the A loop are dramatically different, suggesting that a structural rearrangement of the A loop must occur on docking into the peptidyltransferase center. Possible roles of this docking event, the shifted pKa of C2556 and the U2552 2'-O-methylation in the mechanism of translation, are discussed. Solution structure of the A loop of 23S ribosomal RNA.,Blanchard SC, Puglisi JD Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):3720-5. Epub 2001 Mar 20. PMID:11259644 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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