Characterization of a Nucleotide-Binding Domain Associated with Neisserial Iron Transport

ABSTRACT The fbpABC operon in Neisseria gonorrhoeae encodes an ATP-binding cassette transporter required for iron uptake from the host ferric binding proteins. The gene for the nucleotide-binding domain (fbpC) expressed in Escherichia coli has intrinsic ATPase activity (0.5 mmol/min/mg) uncoupled from the iron transport process. The FbpC E164D mutant is found to have a 10-fold reduction in specific activity. FbpC is covalently modified by 8-azido-[γ32P]ATP, indicating that FbpC is a functional ATPase that likely combines with FbpB to form a ferric iron transporter.