CERTAIN ASPECTS OF STREPTOMYCIN INHIBITION OF PROTEIN SYNTHESIS IN SERRATIA MARCESCENS

The action of streptomycin on protein synthesis was examined in vivo and in vitro with Serratia marcescens. At lethal concentrations of streptomycin (10μg/ml and above) inhibition of protein synthesis and cell death appear to be causally related. Lower concentrations of the antibiotic (4-5μg/ml) do not reduce protein synthesis, growth or the viability of the sensitive cells even after prolonged incubation in the presence of the drug. However, ribosomes isolated from cells so treated show partial reduction of ammo acid incorporation in vitro in the absence of added streptomycin. Evidence suggests that subtle structural defects induced during ribosomal synthesis in the presence of the antibiotic and binding of streptomycin to the ribosomes together account for the defective ribosomal functioning during protein synthesis in vitro.