title: Mechanisms of RNA catalysis.
abstract: Ribozymes are RNA molecules that act as chemical catalysts. In contemporary cells, most known ribozymes carry out phosphoryl transfer reactions. The nucleolytic ribozymes comprise a class of five structurally-distinct species that bring about site-specific cleavage by nucleophilic attack of the 2'-O on the adjacent 3'-P to form a cyclic 2',3'-phosphate. In general, they will also catalyse the reverse reaction. As a class, all these ribozymes appear to use general acid-base catalysis to accelerate these reactions by about a million-fold. In the Varkud satellite ribozyme, we have shown that the cleavage reaction is catalysed by guanine and adenine nucleobases acting as general base and acid, respectively. The hairpin ribozyme most probably uses a closely similar mechanism. Guanine nucleobases appear to be a common choice of general base, but the general acid is more variable. By contrast, the larger ribozymes such as the self-splicing introns and RNase P act as metalloenzymes.
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, MSI/WTB Complex, Dow Street, Dundee DD1 5EH, UK. d.m.j.lilley@dundee.ac.uk
authors.forename: David M J
authors.initials: DM
authors.lastname: Lilley
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D004722:Endoribonucleases / Q000737:chemistry*; D004789:Enzyme Activation; D007438:Introns; D009711:Nucleotides / Q000737:chemistry; D010458:Peptidyl Transferases / Q000737:chemistry; D012313:RNA / Q000737:chemistry*; D012326:RNA Splicing; D016337:RNA, Catalytic / Q000737:chemistry*; D017381:Spliceosomes / Q000737:chemistry; D013379:Substrate Specificity
chemical_list: D009711:Nucleotides; D016337:RNA, Catalytic; C418481:hairpin ribozyme; D012313:RNA; D010458:Peptidyl Transferases; D004722:Endoribonucleases; C438195:varkud satellite ribozyme