Poly amine Requirement for Streptomycin Action on Protein Synthesis in Bacteria

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Abstract
The effect of streptomycin on polypeptide synthesis in vivo and in vitro was investigated using polyamine auxotrophic mutants of Escherichia coli grown in the presence or in the absence of putrescine. Streptomycin caused a marked inhibition of protein synthesis in polyamine-supplemented cells. Bacteria starved for polyamines were less sensitive to the action of the antibiotic. Neomycin, kanamycin and kasugamycin had a behavior similar to streptomycin; spectinomycin, gentamicin and tetracycline brought about a strong inhibition of protein synthesis both in polyamine-starved and unstarved bacteria. The increase of misreading induced by the addition of streptomycin in vitro was higher in extracts derived from bacteria cultivated in the presence of polyamines. This effect was observed in cell-free systems of streptomycin-sensitive and resistant strains. Spermidine added in vitro caused an improvement in the accuracy of translation. Analysis of sodium dodecyl sulfate/polyacrylamide gel electrophoresis of the labeled polypeptides synthesized in vivo suggests that the starvation for polyamine or the presence of streptomycin may lead to premature termination with the appearance of unfinished peptide chains.