title: Identification of phosphate groups involved in metal binding and tertiary interactions in the core of the Neurospora VS ribozyme.
abstract: We have used ethylation protection experiments and modification interference using phosphorothioate nucleosides to identify phosphate groups involved in the magnesium-dependent tertiary structure and function of the VS ribozyme, a small, self-cleaving RNA. Phosphorothioate interference-rescue experiments in the presence of the thiophilic manganese ion implicate four phosphate groups in direct metal ion binding. Phosphorothioate substitution also creates a new manganese binding site that increases the cis cleavage rate of the ribozyme, possibly by disrupting an inhibitory structure. Interpreting these data in the context of a recently developed structural model shows that almost all of the important phosphate groups are located in the central core of the ribozyme. The model suggests roles for certain phosphate groups in particular steps of RNA folding and identifies a candidate region for the active site of the ribozyme.
authors.affiliation: Department of Molecular and Medical Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
authors.forename: V D
authors.initials: VD
authors.lastname: Sood
authors.forename: T L
authors.initials: TL
authors.lastname: Beattie
authors.forename: R A
authors.initials: RA
authors.lastname: Collins
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002413:Cations, Divalent / Q000378:metabolism; D005038:Ethylnitrosourea / Q000378:metabolism; D007700:Kinetics; D015636:Magnesium Chloride / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008670:Metals / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009491:Neurospora / Q000201:enzymology* / Q000235:genetics; D009690:Nucleic Acid Conformation; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism*; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism; D013873:Thionucleotides / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D008670:Metals; D010710:Phosphates; D016337:RNA, Catalytic; D013873:Thionucleotides; D015636:Magnesium Chloride; D008345:Manganese; D005038:Ethylnitrosourea