Mechanism of action of an inhibitor from Proteus vulgaris on cell-free protein synthesis by Escherichia coli B

Abstract

An inhibitory substance(s) has been found in S-30 fractions from Proteus vulgaris which prevented an Escherichia coli B cell-free system from incorporating a mixture of 14C-amino acids, L-phenylalanine-14C, or L-lysine-14C into protein, as directed by natural messenger ribonucleic acid, polyuridylic acid, or polyadenylic acid respectively. Similar results were obtained when the inhibitor was isolated from S-100 fractions by using dialysis, concentration of the dialysate by flash evaporation, hydrolysis, evaporation to dryness, dissolution to the original volume in distilled water, and neutralization. The effect of the inhibitor on the various individual reactions involved in protein synthesis was examined. No effect was found on the activation of amino acids as determined by the formation of L-phenylalanine-14C hydroxamate isolated chromatographically or by adenosine triphosphate – pyrophosphate exchange. Also no inhibition of L-phenylalanine-14C attachment to transfer ribonucleic acid occurred. However, ribosome-dependent reactions were markedly inhibited. The mechanism of action of the inhibitor appeared to be the prevention of binding of phenylalanyl-transfer ribonucleic acid to the ribosomes.