Structural Basis of Transfer Ribonucleic Acid Function

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The goals of this research are to define the sequence and structural elements of transfer ribonucleic acid (tRNA) required for its recognition by proteins. Of particular interest is the recognition of E. coli tRNA for amino acid valine (tRNAVa1) by aminoacyl-tRNA synthetases and by the tRNA modifying enzyme, tRNA (uracil-5-)methyltransferase. Detailed understanding of these interactions will clarify questions concerning the fidelity of protein synthesis, the mechanisms of tRNA modification, and the role of modified nucleosides in tRNA function. The elements of tRNAVa1 essential for its recognition by valyl-tRNA synthetase (VRS) will be determined by examining the kinetics of reaction of tRNAVa1 variants. Minimal requirements for synthetase recognition will be explored with tRNA fragments containing the essential recog- nition elements of tRNAVa1. The structure of these mutant tRNAs will be probed by 19F NMR spectroscopy of tRNAVa1 labe- led with fluorine. Fluorinated tRNAVa1 is ideally suited for such studies because it remains fully functional and contains highly sensitive 19F probes distributed throughout all the helical stems and the loops of the tRNA molecule where they can serve to monitor local structural changes.