Self-Incorporation of coenzymes by ribozymes |
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Authors: | Ronald R. Breaker Gerald F. Joyce |
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Affiliation: | (1) Departments of Chemistry and Molecular Biology, The Scripps Research Institute, 10666 North Torrey Pines Road, 92037 La Jolla, CA, USA |
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Abstract: | RNA molecules that are assembled from the four standard nucleotides contain a limited number of chemical functional groups, a characteristic that is generally thought to restrict the potential for catalysis by ribozymes. Although polypeptides carry a wider range of functional groups, many contemporary protein-based enzymes employ coenzymes to augment their capabilities. The coenzymes possess additional chemical moieties that can participate directly in catalysis and thereby enhance catalytic function. In this work, we demonstrate a mechanism by which ribozymes can supplement their limited repertoire of functional groups through RNA-catalyzed incorporation of various coenzymes and coenzyme analogues. The group I ribozyme of Tetrahymena thermophila normally mediates a phosphoester transfer reaction that results in the covalent attachment of guanosine to the ribozyme. Here, a shortened version of the ribozyme is shown to catalyze the self-incorporation of coenzymes and coenzyme analogues, such as NAD+ and dephosphorylated CoA-SH. Similar ribozyme activities may have played an important role in the RNA world, when RNA enzymes are thought to have maintained a complex metabolism in the absence of proteins and would have benefited from the inclusion of additional functional groups.Correspondence to: G.F. Joyce |
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Keywords: | Terahymena thermophila Group I intron Self-splicing RNA RNA world Nicotinamide Coenzyme A |
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