title: Crystal structure and mechanistic investigation of the twister ribozyme.
abstract: We present a crystal structure at 2.3-Å resolution of the recently described nucleolytic ribozyme twister. The RNA adopts a previously uncharacterized compact fold based on a double-pseudoknot structure, with the active site at its center. Eight highly conserved nucleobases stabilize the core of the ribozyme through the formation of one Watson-Crick and three noncanonical base pairs, and the highly conserved adenine 3' of the scissile phosphate is bound in the major groove of an adjacent pseudoknot. A strongly conserved guanine nucleobase directs its Watson-Crick edge toward the scissile phosphate in the crystal structure, and mechanistic evidence supports a role for this guanine as either a general base or acid in a concerted, general acid-base-catalyzed cleavage reaction.
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, Medical Sciences Institute/Wellcome Trust Building (MSI/WTB) Complex, University of Dundee, Dundee, UK.
authors.forename: Yijin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, Medical Sciences Institute/Wellcome Trust Building (MSI/WTB) Complex, University of Dundee, Dundee, UK.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Wilson
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, Medical Sciences Institute/Wellcome Trust Building (MSI/WTB) Complex, University of Dundee, Dundee, UK.
authors.forename: Scott A
authors.initials: SA
authors.lastname: McPhee
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, Medical Sciences Institute/Wellcome Trust Building (MSI/WTB) Complex, University of Dundee, Dundee, UK.
authors.forename: David M J
authors.initials: DM
authors.lastname: Lilley
mesh_terms: D000225:Adenine / Q000737:chemistry; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012275:Oryza / Q000737:chemistry; D012313:RNA / Q000737:chemistry*; D016337:RNA, Catalytic / Q000737:chemistry*; D018749:RNA, Plant / Q000737:chemistry
chemical_list: D016337:RNA, Catalytic; D018749:RNA, Plant; D012313:RNA; D000225:Adenine