title: The crystal structure of an all-RNA hammerhead ribozyme: a proposed mechanism for RNA catalytic cleavage.
abstract: We have solved the crystal structure of an all-RNA hammerhead ribozyme having a single 2'-O-methyl cytosine incorporated at the active site to prevent cleavage. The conditions used differ from those in another recent solution in four significant ways: first, it is an all-RNA ribozyme rather than a DNA-RNA hybrid; second, the connectivity of the ribozyme backbone strands is different; third, the crystals were grown in the presence of a much lower concentration of salt; and fourth, the crystal packing scheme is very different. Nevertheless, the three-dimensional structure of the all-RNA hammerhead ribozyme is similar to the previous structure. Five potential Mg(II)-binding sites are identified, including one positioned near the ribozyme catalytic pocket. Upon this basis, as well as upon comparisons with the metal-binding sites in the structurally homologous uridine turn of tRNAPhe, we propose a mechanism for RNA catalytic cleavage.
authors.affiliation: Medical Research Council, Laboratory of Molecular Biology, Cambridge, England.
authors.forename: W G
authors.initials: WG
authors.lastname: Scott
authors.forename: J T
authors.initials: JT
authors.lastname: Finch
authors.forename: A
authors.initials: A
authors.lastname: Klug
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D003562:Cytidine / Q000031:analogs & derivatives; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D008274:Magnesium / Q000378:metabolism; D008670:Metals; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D012360:RNA, Transfer, Phe / Q000737:chemistry / Q000378:metabolism
chemical_list: D008670:Metals; D016337:RNA, Catalytic; D012360:RNA, Transfer, Phe; C052203:2'-O-methylcytidine; D003562:Cytidine; D012313:RNA; D004247:DNA; D008274:Magnesium