A plasmid-encoded arsenite pump produces arsenite resistance in Escherichia coli |
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Authors: | B P Rosen M G Borbolla |
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Institution: | Department of Biological Chemistry University of Maryland School of Medicine Baltimore, MD 21201 USA |
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Abstract: | The arsenate resistance operon of R-factor R773, a conjugative resistance plasmid, has two functional regions, a promoter-proximal region encoding resistance to arsenite and antimonate, and a promoter-distal one encoding arsenate resistance. Cells bearing arsenite resistance plasmids exhibited reduced accumulation of 74AsO2-. When resistant cells were depleted of endogenous energy reserves and then loaded with 74AsO2-, active extrusion of the ion was observed when an energy source was supplied. Intracellular ATP was required for extrusion, but a proton motive force was neither necessary nor sufficient. An arsenite-sensitive mutant was unable to extrude arsenite, while an arsenate-sensitive mutant had normal arsenite transport. These results suggest that the action of a plasmid-encoded primary arsenite efflux pump is the mechanism of arsenite resistance. |
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Keywords: | arsenate arsenite antimonate kilobase pairs |
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