4b5r | pdb_00004b5r

SAM-I riboswitch bearing the H. marismortui K-t-7

spinqualitylabelsall models 4b5r, resolution 2.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4b5r is a 1 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: BA, K, SAM Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The k-turn is a widespread structural motif that introduces a tight kink into the helical axis of double-stranded RNA. The adenine bases of consecutive G*A pairs are directed toward the minor groove of the opposing helix, hydrogen bonding in a typical A-minor interaction. We show here that the available structures of k-turns divide into two classes, depending on whether N3 or N1 of the adenine at the 2b position accepts a hydrogen bond from the O2' at the -1n position. There is a coordinated structural change involving a number of hydrogen bonds between the two classes. We show here that Kt-7 can adopt either the N3 or N1 structures depending on environment. While it has the N1 structure in the ribosome, on engineering it into the SAM-I riboswitch, it changes to the N3 structure, resulting in a significant alteration in the trajectory of the helical arms. The plasticity of a structural motif in RNA: Structural polymorphism of a kink turn as a function of its environment.,Daldrop P, Lilley DM RNA. 2013 Jan 16. PMID:23325110 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Riboswitch

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