ASSOCIATION OF FUSIDIC ACID SENSITIVITY WITH G FACTOR IN A PROTEIN-SYNTHESIZING SYSTEM

It was observed that fusidic acid and related steroidal antibiotics inhibit protein synthesis in the in vivo and in vitro bacterial systems (Yamaki, 1965; Harvey et al., 1966; Tanaka et al., 1967). In an E. coli system, they inhibit ribosome-dependent GTPase reaction with G factor of transfer enzymes, and the grade of inhibition is parallel to that of polypeptide synthesis. It was further suggested by the experiments, using puromycin reaction, that the antibiotics inhibit translocation of peptidyl-tRNA on the ribosomes (Tanaka et al., 1968). Fusidic acid inhibits GTPase activity, observed in combination of the ribosomes and G factor. The localization of fusidic acid sensitivity was further studied with respect to the ribosomes and G factor of drug-sensitive E. coli cells and those of resistant cells. The results are presented in this communication. It was demonstrated that the fusidic acid sensitivity is associated with G factor, but not with the ribosomes. © 1968.