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Published July 2002 | Published
Journal Article Open

Dissection of a metal-ion-mediated conformational change in Tetrahymena ribozyme catalysis


Conformational changes are often required for the biological function of RNA molecules. In the Tetrahymena group I ribozyme reaction, a conformational change has been suggested to occur upon binding of the oligonucleotide substrate (S) or the guanosine nucleophile (G), leading to stronger binding of the second substrate. Recent work showed that the two substrates are bridged by a metal ion that coordinates both the nonbridging reactive phosphoryl oxygen of S and the 2′-OH of G. These results suggest that the energy from the metal ion[bull ]substrate interactions is used to drive the proposed conformational change. In this work, we provide an experimental test for this model. The results provide strong support for the proposed conformational change and for a central role of the bridging metal ion in this change. The results from this work, combined with previous data, allow construction of a two-state model that quantitatively accounts for all of the observations in this and previous work. This model provides a conceptual and quantitative framework that will facilitate understanding and further probing of the energetic and structural features of this conformational change and its role in catalysis.

Additional Information

© 2002 RNA Society. The Authors acknowledge that six months after the full-issue publication date, the Article will be distributed under a Creative Commons CC-BY-NC License (Attribution-NonCommercial 4.0 International License, http://creativecommons.org/licenses/by-nc/4.0/). Published online by Cambridge University Press: 20 August 2002. We thank Dr. F. Eckstein for the generous gift of 2'-aminoguanosine, L. Beigelman for oligonucleotides, and K. Karbstein and L. Bartley for permission to cite unpublished results. This work was supported by National Institutes of Health Grant GM49243 to D.H.

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