On the relation between ribonucleic acid synthesis and peptide chain initiation in E. coli.

Abstract

Trimethoprim, an inhibitor of dihy-drofolate reductase, stopped the synthesis of both RNA and protein in E. coli cells with stringent control of RNA synthesis. Chloram-phenicol or tetracycline, added after trimethoprim, restored the synthesis of RNA, but not of protein. In E. coli cells with relaxed control of RNA synthesis, trimethoprim stopped protein synthesis, but not RNA synthesis. It was shown earlier that in extracts of trimethoprim-treated cells, amino acid incorporation (directed by f2 RNA) depended on addition of N-formylmethionyl-tRNA. The above results and considerations indicate that the synthesis of RNA and of protein in E. coli strains with stringent control depends directly or indirectly on N-formylmethionyl-tRNA, a compound known to be the major, if not the sole, peptide chain initiator inE. coli.