This award will support research on two aspects of RNA catalysis. The first is to define the substrate specificity of P RNA, the catalytic component of B. subtilis tRNA processing enzyme RNaseP. Carefully designed mutations in the established domain of yeast tRNA-phe precursor will be assayed in the RNA dependent cleavage reaction. Fluorescent assays will be developed to identify the binding and cleavage steps. The second is to ascertain the mechanism of Pb and Mg dependent cleavage of yeast tRNA-phe. Mutant tRNAs with unique deoxy-2- O'methyl and alpha-thio-phosphate substitutions will be prepared to test a model of Klug derived from X-ray diffraction data. The results will greatly aid our understanding of how RNA catalysis takes place, the evolution of enzymes and the origin of life on earth.
