Interaction between tRNA and Aminoacyl-tRNA Synthetase in the Valine and Phenylalanine Systems from Yeast

Abstract

Much work has been devoted to studies of the interaction between tRNAs and aminoacyl-tRNA synthetases. The aim was to understand the mechanisms that govern the specificity of the tRNA aminoacylation reaction (for recent general reviews, see Kisselev and Favorova 1974; Söll and Schimmel 1974; Goddard 1977; Ofengand 1977). In the early days, indirect approaches to this problem were used; recently, direct approaches have been introduced.

The indirect approaches included perturbing the primary structure of tRNA by chemical or genetic means, excising small sequences in tRNA and correlating these perturbations with the activity of the modified molecules, or comparing the sequences of different tRNAs recognized by the same aminoacyl-tRNA synthetase. The direct approaches include measuring the inhibition of the tRNA aminoacyl-tRNA synthetase interaction caused by various factors (e.g., oligonucleotides or ionic strength) or studying the shielding of some areas of the tRNA by the aminoacyl-tRNA synthetase against RNases, oligonucleotides, or chemicals; they also include measurements by physical means of the thermodynamic parameters involved in the interaction between the aminoacyl-tRNA synthetase and intact or fragmented tRNA and the determination of the contact zones between the two macromolecules by cross-linking methods (for additional details, see reviews by Loftfield 1972; Schimmel 1977; Smith 1977). The interpretation of the results of most of these approaches has been greatly facilitated by knowledge of the structures of tRNA (Rich and RajBhandary 1976; Dirheimer et al., this volume) and aminoacyl-tRNA synthetase (Irwin et al. 1976; Zelwer et al. 1976; Winter and Hartley 1977). At this stage, however, this...