FbpC is not essential for iron acquisition in Neisseria gonorrhoeae

The fbpABC locus of Neisseria gonorrhoeae has been proposed to encode a per iplasmic protein-dependent iron transport system. Although the function of the gonococcal FbpA protein has been well characterized and its role as a p eriplasmic binding protein is well defined, little is known about the funct ion of the FbpB and FbpC proteins. To define the function of the gonococcal FbpC protein, an N. gonorrhoeae F62 fbpC mutant was constructed by inserti onal inactivation with the kanamycin gene. The N. gonorrhoeae F62 fbpC muta nt was observed to grow with heme, transferrin, or ferric nitrate as the sc ale exogenous iron source, indicating that the gonococcal FbpC protein is n ot absolutely required for growth with these iron sources. In previous stud ies we were unable to detect fbpB- or fbpC-specific transcripts by Northern analysis. Reverse transcription-PCR analysis with RNA obtained from N. gon orrhoeae F62 grown under iron-replete and -depleted conditions detected fbp A and fbpAB transcripts but failed to detect fbpC or fbpBC transcripts. The se results indicate that FbpC does not play a pivotal role in iron transpor t in N. gonorrhoeae and suggest that additional ABC transport systems are f unctional in the gonococcus for the acquisition of iron.