BIOL 133 |
| RNA-enzymes (ribozymes) are catalysts whose active sites are composed entirely of nucleic acid groups. Biologically-occurring ribozymes include several self-splicing RNAs and also the proposed active sites of the ribosome and spliceosome. Determining the mechanisms of ribozymes is an active area of research that has driven technical developments in methods used to monitor RNA folding and structure. At physiological ionic strength, the activities of most ribozymes are sensitive to added Mg(II). This metal ion requirement may influence RNA folding, chemistry, or both. We are investigating the potential of site-directed spin labeling (SDSL) and EPR spectroscopic methods to monitor Mg(II)-induced RNA structural changes. SDSL-EPR affords a complementary approach to fluorescence-based methods for investigating problems in RNA structural biology. Distance measurements between two attached nitroxide moieties are performed using both CW and pulsed (DEER) EPR methods. Folding-induced dynamic changes at singly labeled sites are monitored by spectral lineshape analysis. These techniques have been applied to model RNA duplexes (Kim et al., Chem. Biol. 2004, 11, p. 939; Bowman et al., App. Mag. Res. 2004, 26, p. 23), the hammerhead ribozyme (Kim et al., JACS 2005, 127, p. 187), and the P4-P6 subdomain of the Group I intron. The current results demonstrate the strong potential of SDSL-EPR methods to monitor changes in RNA structure, including both large-scale and more subtle rearrangements. |
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Chemistry and Metabolism
4:30 PM-6:30 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Division of Biological Chemistry |