Folding and catalysis of the hairpin ribozyme.
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.
Wilson
T J
TJ
Cancer Research U.K. Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, UK.
Nahas
M
M
Ha
T
T
Lilley
D M J
DM
D002384:Catalysis; D009690:Nucleic Acid Conformation; D010710:Phosphates / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D010710:Phosphates; D016337:RNA, Catalytic; C418481:hairpin ribozyme