title: Folding and catalysis of the hairpin ribozyme.
abstract: The active form of the hairpin ribozyme is brought about by the interaction of two formally unpaired loops. In a natural molecule, these are present on two adjacent arms of a four-way junction. Although activity can be obtained in molecules lacking this junction, the junction is important in the promotion of the folded state of the ribozyme under physiological conditions, at a rate that is faster than the chemical reaction. Single-molecule fluorescence resonance energy transfer studies show that the junction introduces a discrete intermediate into the folding process, which repeatedly juxtaposes the two loops and thus promotes their docking. Using single-molecule enzymology, the cleavage and ligation rates have been measured directly. The pH dependence of the rates is consistent with a role for nucleobases acting in general acid-base catalysis.
authors.affiliation: Cancer Research U.K. Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Wilson
authors.forename: M
authors.initials: M
authors.lastname: Nahas
authors.forename: T
authors.initials: T
authors.lastname: Ha
authors.forename: D M J
authors.initials: DM
authors.lastname: Lilley
mesh_terms: D002384:Catalysis; D009690:Nucleic Acid Conformation; D010710:Phosphates / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010710:Phosphates; D016337:RNA, Catalytic; C418481:hairpin ribozyme