title: Effects of colicins E1 and K on permeability to magnesium and cobaltous ions.
abstract: The energy-dependent exchange of intracellular Mg(2+) with extracellular Mg(2+) or Co(2+) is inhibited by colicin E1 and, less strongly, by colicin K. Treatment with either colicin causes a net loss of intracellular Mg(2+). This loss begins immediately in cells treated with colicin E1, but in colicin K-treated cells the onset of Mg(2+) loss is delayed 1 to 10 min, depending upon the temperature and the multiplicity of colicin K. Both colicins differ from chemical inhibitors of energy-yielding metabolism; energy poisons block transport of Mg(2+) and Co(2+), but both colicins increase passive permeability to Mg(2+) and Co(2+). Inhibitors of energy-yielding metabolism (and of Mg(2+) exchange) block the initiation of Mg(2+) loss by either colicin, but do not stop colicin-promoted efflux once it has begun. Colicin E1 added before colicin K prevents the more rapid Mg(2+) efflux characteristic of colicin K-treated cells. Quantitative comparisons of the effects of colicins E1 and K upon permeability to Mg(2+) and Co(2+) lead us to conclude that the two colicins are not identical in their mode of action.
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D002127:Calcium Isotopes; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003035:Cobalt / Q000378:metabolism*; D003036:Cobalt Isotopes; D003087:Colicins / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D009154:Mutation; D011868:Radioisotopes; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013696:Temperature; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D002127:Calcium Isotopes; D003036:Cobalt Isotopes; D003087:Colicins; D006027:Glycosides; D011868:Radioisotopes; D013439:Sulfhydryl Reagents; D014475:Uncoupling Agents; D003035:Cobalt; D008274:Magnesium