title: Functional equivalence of the uridine turn and the hairpin as building blocks of tertiary structure in the Neurospora VS ribozyme.
abstract: Mutational, kinetic, and chemical modification experiments show that one of the three-way helical junctions in the Neurospora VS ribozyme contains a uridine turn that is important for organizing the functional three-dimensional structure of this junction. Disruption of the uridine turn disrupts the structure of the junction and decreases the self-cleavage activity of the ribozyme; however, substitution of the uridine turn with a variety of different hairpins, thereby transforming the three-way junction into a four-way junction, maintains catalytic activity. Chemical modification structure probing reveals that both the native junction and the hairpin-containing junction support the same tertiary interactions required elsewhere in the ribozyme for catalysis. These observations show that functionally equivalent three-dimensional RNA structures can be built from different secondary structure elements.
authors.affiliation: Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
authors.forename: V D
authors.initials: VD
authors.lastname: Sood
authors.forename: R A
authors.initials: RA
authors.lastname: Collins
mesh_terms: D001483:Base Sequence; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009491:Neurospora / Q000201:enzymology* / Q000235:genetics*; D023282:Nuclease Protection Assays; D009690:Nucleic Acid Conformation; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D014529:Uridine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D016337:RNA, Catalytic; D004722:Endoribonucleases; C438195:varkud satellite ribozyme; D014529:Uridine