Cloning, sequencing, and characterization of the gene encoding FrpB, a major iron-regulated, outer membrane protein of Neisseria gonorrhoeae.

FrpB (for Fe-regulated protein B) is a 76-kDa outer membrane protein that is part of the iron regulon of Neisseria gonorrhoeae and Neisseria meningitidis. The frpB gene from gonococcal strain FA19 was cloned and sequenced. FrpB was homologous to several TonB-dependent outer membrane receptors of Escherichia coli as well as HemR of Yersinia enterocolitica and CopB of Moraxella catarrhalis. An omga insertion into the frpB coding sequence caused a 60% reduction in 55Fe uptake from heme, but careful analysis suggested that this effect was nonspecific. While FrpB was related to the family of TonB-dependent proteins, a function in iron uptake could not be documented.