Physical Studies of tRNA in Solution

Abstract

RNA-RNA interactions are formed and broken during the complex process of ribosome-mediated protein synthesis. In addition to the obvious interaction between the mRNA codons and the two tRNA anticodons, proposals have included binding between (1) tRNA and 5S RNA (Erdman 1976), (2) 5S RNA and 23S RNA (Herr and Noller 1975), (3) 23S RNA and 16S RNA (van Duin et al. 1976), (4) 16S RNA and tRNA (Noller and Chaires 1972), and (5) 16S RNA and mRNA during initiation (Shine and Delgarno 1974; Steitz and Jakes 1975). Clearly, a full understanding of the detailed mechanism of protein synthesis will require study of the equilibria and dynamics of RNA conformational changes. tRNA has been the most convenient and intensively studied system of this kind.

Our knowledge of the molecular mechanisms of functional RNA conformational changes is in its infancy, usually limited to direct (Steitz and Jakes 1975) or indirect (Noller and Chaires 1972; Shine and Delgarno 1974; Herr and Noller 1975; Erdman 1976; van Duin et al. 1976) evidence that a pairing occurs. In contrast, conformational changes of isolated tRNA molecules have been intensively studied, especially between 1965 and 1975 (Crothers and Cole 1978). These early studies established the general conformational and ion-binding properties of tRNA and have now given way to more sophisticated techniques used to study specialized properties, of the kind reported by Reid and Hurd, Johnston and Redfield, and Potts et al. (all this volume). In particular, nuclear magnetic resonance (NMR) studies play a central role in present...