Vanadate and bafilomycin A1 are potent inhibitors of the ATPase activity of the reconstituted bacterial ATP-binding cassette transporter for maltose (MalFGK2).

Vanadate and Bafilomycin A1 were shown to inhibit the ATPase activity of the reconstituted binding protein-dependent ATP-binding Cassette (ABC) transporter for maltose (MalFGK2) of Salmonella typhimurium in the micromolar range. This is in sharp contrast to the recent finding that the isolated ATPase subunit MalK was insensitive to both compounds. Our data provide the first experimental evidence for the view that functional coupling of the ATPase domain of an ABC transporter to the membrane-integral domains is crucial for conferring sensitivity to vanadate and bafilomycin A1. Possible consequences for the mode of action of ABC transport proteins are discussed.