Studies on tRNA Conformation and Ribosome Interaction with Fluorescent tRNA Derivatives

Abstract

Specific interactions of tRNA with aminoacyl-tRNA synthetases and with mRNA-programmed ribosomes are key steps in protein biosynthesis. It is the precision of these two steps that determines the accuracy of codon-dependent amino acid incorporation into protein. Structure-function relationships of the common reactant of the two steps, the tRNA, have been studied extensively by using a variety of approaches (see summaries by Rich and RajBhandary 1976; Schimmel 1977; Holbrook et al. 1978). Although a detailed picture of the structure of tRNA and an understanding of the various steps of protein synthesis have emerged, little is known concerning the interactions of tRNA on the molecular level. Furthermore, the conformational changes of the tRNA, which are indicated by a number of studies, have not yet been fully established.

Fluorescence spectroscopy has proved to be useful in both thermodynamic and kinetic studies of conformational changes and interactions of macromolecules. In addition, information may be obtained about the environment and the mobility of the fluorophor (Cantor and Tao 1971). In this paper, experiments on the use of fluorescent tRNA derivatives in tRNA-conformation and ribosome-interaction studies are reviewed. Studies on the interaction of such derivatives with synthetases have been published (Pachmann et al. 1973) and will not be included here.

PREPARATION AND CHARACTERIZATION OF FLUORESCENT tRNA DERIVATIVES
A number of fluorescent compounds have been introduced into tRNA by covalent attachment to odd bases carrying unique functional groups (see, e.g., Yang and Söll 1974) or to the aminoacyl moiety of aminoacylated tRNA (see, e.g., Lynch and Schimmel...