A plasmid-encoded arsenite pump produces arsenite resistance in Escherichia coli.
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.
D000255:Adenosine Triphosphate / Q000378:metabolism; D001151:Arsenic / Q000494:pharmacology*; D018053:Arsenites; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D010957:Plasmids
D018053:Arsenites; D000255:Adenosine Triphosphate; C015001:arsenite; D001151:Arsenic