title: The plasticity of a structural motif in RNA: structural polymorphism of a kink turn as a function of its environment.
abstract: 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.
authors: Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, United Kingdom.
authors: Peter
authors: P
authors: Daldrop
authors: David M J
authors: DM
authors: Lilley
mesh_terms: D020029:Base Pairing; D019614:Haloarcula marismortui / Q000235:genetics; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry*; D019642:RNA, Archaeal / Q000737:chemistry*; D058928:Riboswitch
chemical_list: D019642:RNA, Archaeal; D058928:Riboswitch; D012313:RNA