Transfer RNA: Discovery, Early Work, and Total Synthesis of a tRNA Gene

Abstract

Biochemical studies of protein synthesis in vitro got under way in early 1950s. The fundamental concept arose that specificity in protein synthesis was primarily governed by loading of every amino acid onto a cognate soluble RNA by an enzyme specific for that amino acid. The RNAs involved began to be known as transfer RNAs (tRNAs), and activating enzymes came to be known as aminoacyl-tRNA synthetases. With elucidation of genetic code in DNA, the code in emerged as a central problem in molecular biology of protein biosynthesis, and structure and function in tRNA became focus of attention in many laboratories. In tRNA field, Abelson and Miller and their colleagues have carried out studies on aminoacylation specificity of tRNAs in vivo, using synthetic genes for suppressor tRNAs. This approach, together with RNA synthesis, for investigation of sequence-dependent aminoacylation of RNA oligonucleotides in vitro has proved most useful for studying aminoacyl tRNA synthetases-tRNA recognitions in vivo. Totally synthetic genes lend themselves well to systematic mutagenesis by principle of fragment (cassette) replacement. Structure-function studies on integral membrane proteins such as bacteriorhodopsin, sensory rhodopsin, and vertebrate photoreceptor rhodopsin have used exclusively synthetic gene approach. A large number of chimeric genes of visual color pigments were synthesized by Oprian and colleagues for precise studies of spectral tuning in vision.