Synthesis and Functions of the -C-C-A Terminus of Transfer RNA

This chapter discusses the established central role of tRNA in the biosynthesis of proteins. Numerous sequence analyses in the past several years have confirmed the existence of this terminal sequence in all tRNA molecules specific for most amino acids, independent of their biological sources. In fact, the sequence determination of a tRNA involved exclusively in cell wall synthesis revealed that the -C-C-A terminus is present in molecules used for processes other than protein synthesis. It reviews the studies dealing with the synthesis and function of the -C-C-A terminus of tRNA. Currently, other than the anticodon, the only part of the tRNA molecule assigned a specific function is the 3'-terminus. This region of tRNA is particularly amenable to study as it is possible to modify its structure without affecting the rest of the nucleic acid chain by use of the enzyme tRNA nucleotidyltransferase. This enzyme is itself of interest and is discussed, because its mode of action is particularly pertinent to an understanding of nucleic acid recognition and to the mechanism of phosphodiester bond synthesis.