THE MECHANISM OF R-FACTOR MEDIATED ARSENATE RESISTANCE IS AN INDUCIBLE ATP-DRIVEN ARSENATE EFFLUX SYSTEM

Publisher Summary This chapter describes the mechanism of arsenate resistance mediated by the resistance factor R773. The energy source for arsenate efflux is phosphate bond energy, most likely in the form of ATP, and not the electrochemical proton gradient. Vanadate, which inhibits ion-translocating ATPases, is a potent inhibitor of arsenate efflux. The energetics of the efflux reaction suggests that the transport system is an arsenate-translocating ATPase. In contrast, the proton motive force rather than ATP is the energy source for calcium extrusion, and secondary calcium/proton exchange rather than a calcium-translocating ATPase has been found to be the mechanism of calcium extrusion in most bacteria.