Cadmium and manganese transport in Staphylococcus aureus membrane vesicles.
The presence of plasmid gene cadB did not affect Cd2+ accumulation, whereas plasmid gene cadA reduced Cd2+ accumulation by whole cells but not by membrane vesicles. Membrane vesicle studies indicated that Cd2+ uptake occurred via the Mn2+ transport system which was energized by the membrane electrical potential. Mn2+ and Cd2+ were competitive inhibitors of each other's transport, with Km's of 0.95 microM Mn2+ and 0.2 microM Cd2+. The kinetic parameters were nearly identical with vesicles prepared from sensitive and resistant cells, indicating that the cadA-encoded Cd2+ efflux system was inoperative in membrane vesicle preparations. Experiments with energy-inhibited cells indicated that the cadB gene product may bind Cd2+.
D001693:Biological Transport, Active; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D007700:Kinetics; D008345:Manganese / Q000378:metabolism*; D011815:R Factors; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism*
D002104:Cadmium; D008345:Manganese