Synthesis of Polyphenylalanine in a Cell-free System from E. coli A19: Ribosomal Binding Sites, Initiation with Formyl-methionyl-tRNA, and Codon-Interaction of Aminoacyl-tRNA

Abstract

Molecular biology deals with specificity relationships between the molecular members of the various functional systems of the cell. The decoding system is the center of gene action and is outlined for the bacterial

cell in Fig. 1. This system involves, (1) Template-controlled enzymatic processes of information transfer: The synthesis of the different species of RNA and of protein. (2) Nontemplate-controiled enzymic reactions: The synthesis of aminoacyl-tRNA. (3) Formation of structural complexes by macromolecules: The spontaneous combination of ribosomal RNA and proteins to form ribosomes, and the interaction of the repressor (R) and the operator (o) region of DNA to form the repressed state of an operon. The crucial and typical functions in the decoding system are those bringing together biochemical specificities which reside in molecules belonging to different classes of substance: RNA-polymerase transcribes DNA into RNA and aminoacyl-tRNA-synthetases recognize the specific relationships between aminoacids and their corresponding transfer-RNAs. The final translation-problem is thus reduced, from an overall recognition of correspondence between DNA-triplets and aminoacids by the whole decoding system, to a presumed checking of the specific interaction between RNA-triplets, i. e. of codons in mRNA, and of anticodons in aminoacyl-tRNA. This final translation most certainly takes place on the ribosome.