title: Role of ribosome recycling in uptake of dihydrostreptomycin by sensitive and resistant Escherichia coli.
abstract: Exposure of streptomycin-resistant cells to puromycin results in uptake of dihydrostreptomycin comparable to that found with streptomycin-sensitive cells. This finding indicates that the enhanced phase of uptake, previously reported only in sensitive cells, may result from an increase in internal binding sites, presumably run-off ribosomes. The increased uptake of dihydrostreptomycin resulting from exposure to puromycin is greatest in both sensitive and resistant cells at concentrations below 100 microgram/ml. At 100 microgram/ml, exposure to puromycin in vivo results in significant, but not complete, polysome degradation and inhibition of protein synthesis. At 500 microgram/ml, where polysome degradation is complete in less than 2 min and where growth and protein synthesis are inhibited more than 90%, uptake of dihydrostreptomycin by both sensitive and resistant cells is inhibited. Puromycin has no effect on binding of dihydrostreptomycin to 70-S monosomes, as measured by equilibrium dialysis. The increased uptake of dihydrostreptomycin by resistant cells resulting from exposure to puromycin has no effect on viability. Addition of N-ethylmaleimide immediately and completely inhibits the puromycin-induced uptake of dihydrostreptomycin even when added after substantial polysome degradation has occurred.
mesh_terms: D004096:Dihydrostreptomycin Sulfate / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D007612:Kanamycin / Q000494:pharmacology; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism*; D011691:Puromycin / Q000494:pharmacology
chemical_list: D011691:Puromycin; D007612:Kanamycin; D005033:Ethylmaleimide; D004096:Dihydrostreptomycin Sulfate