A BORDETELLA-PERTUSSIS FEPA HOMOLOG REQUIRED FOR UTILIZATION OF EXOGENOUS FERRIC ENTEROBACTIN

The bfeA (Bordetella ferric enterobactin) receptor gene was cloned fro m a Bordetella pertussis chromosomal library by using a screen in Esch erichia coli to detect iron-repressed genes encoding exported proteins translationally fused to the E. coli phoA gene. The bfeA gene encoded a protein with a molecular mass of approximately 80 kDa and about 50% amino acid sequence identity to both the fepA- and pfeA-encoded enter obactin receptors of E. coli and Pseudomonas aeruginosa, respectively. Enterobactin prepared from iron-starved E. coli cultures supported gr owth of B. pertussis and Bordetella bronchiseptica in the presence of the iran chelator ethylenediamine-di-(o-hydroxyphenylacetic acid) (EDD A). Expression of the bfeA gene was induced by low iron availability, and iron-regulated expression appeared to be dependent upon the presen ce of the sequence contained within 370 bp upstream of the bfeA struct ural gene. An internal fragment of the bfeA structural gene and flanki ng regions were shown by Southern analysis to be highly conserved amon g Bordetella species. Insertional inactivation of bfeA in both B. pert ussis and B. bronchiseptica greatly impaired their ability to grow in the presence of enterobactin and EDDA. These findings suggest that ent erobactin produced by other respiratory flora could aid in the coloniz ation of the respiratory tract by Bordetella species.