Inhibition of Protein Synthesis in E. coli Protoplasts by Actinomycin-D

Abstract

Actinomycin-D has been reported to inhibit DNA-dependent RNA synthesis (Goldberg & Rabinowitz, 1962; Hurwitz, Furth, Malamy & Alexander, 1962), but to allow RNA viruses to continue to replicate in animal cells (Reich, Franklin, Shatkin & Tatum, 1961, 1962.) In Gram-positive bacteria this inhibition of RNA synthesis has been followed by an inhibition of protein synthesis (Kirk, 1960; Levinthal, Keynan & Higa, 1962). Actinomycin-D has been reported not to affect E. coli (Hurwitz et al., 1962), most likely because the cell wall is impermeable to actinomycin. We have observed that actinomycin-D at 10 y/ml. will strongly inhibit protein synthesis in protoplasts of E.coli C-3000 without inhibiting the growth of an RNA bacteriophage, MS2 (Davis, Strauss & Sinsheimer, 1961).

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