Structural diversity of self-cleaving ribozymes
Abstract
In vitro selection was used to isolate Mg2+-dependent self-cleaving ribozymes from random sequence. Characterization of representative clones revealed the emergence of at least 12 classes of ribozymes that adopt distinct secondary structure motifs. Only one class corresponds to a previously known structural motif, that of the naturally occurring hammerhead ribozyme. Each ribozyme promotes self-cleavage via an internal phosphoester transfer reaction involving the adjacent 2'-hydroxyl group with a chemical rate enhancement of between 103- and 106-fold greater than the corresponding uncatalyzed rate. These findings indicate that RNA can form a multitude of secondary and tertiary structures that promote cleavage by internal phosphoester transfer. Upon further in vitro selection, a class I ribozyme that adopts an "X motif" structure dominates over all other ribozymes in the population. Thus, self-cleaving RNAs isolated by in vitro selection from random-sequence populations can rival the catalytic efficiency of natural ribozymes.
- Publication:
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Proceedings of the National Academy of Science
- Pub Date:
- May 2000
- DOI:
- 10.1073/pnas.97.11.5784
- Bibcode:
- 2000PNAS...97.5784T
- Keywords:
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- Biochemistry