Streptomycin Uptake via an Inducible Polyamine Transport System in Escherichia coli

Abstract

The rate of uptake of streptomycin by Escherichia coli K12 becomes greatly enhanced after 10–20 min of incubation. Maximal rate of streptomycin and of gentamicin uptake is achieved by preincubation of the cells at 37 °C for 20 min in the presence of 5 μg/ml of streptomycin, kanamycin, gentamicin or neomycin. Spectinomycin and kasugamycin failed to increase streptomycin uptake. Enhanced streptomycin uptake is absolutely energy‐dependent. The uptake of streptomycin by wild type E. coli is much repressed in the presence of glucose. A cya mutant of E. coli which cannot synthesize adenosine 3′:5′‐monophosphate (cyclic AMP) exhibits poor uptake of streptomycin. The addition of cyclic AMP however, induces the uptake of streptomycin in this mutant. Transport of spermidine is ten times increased in the presence of 5 μg/ml streptomycin. The uptake of putrescine is enhanced two‐fold under the same conditions. Increase of uptake is prevented by chloramphenicol. Streptomycin competitively inhibits the transport of spermidine and putrescine. Conversely, spermine, spermidine and putrescine inhibit the uptake of streptomycin. It is concluded from these results that interaction of streptomycin with the ribosomes results in the induction of a polyamine transport system which can be utilized by streptomycin. Copyright © 1978, Wiley Blackwell. All rights reserved