A lipoprotein of Yersinia enterocolitica facilitates ferrioxamine uptake in Escherichia coli.

A cloned fragment of Yersinia enterocolitica DNA complemented the defect in ferrioxamine B uptake of an Escherichia coli fhuE mutant lacking the outer membrane high-affinity transport protein FhuE. Subcloning revealed that a 13.7-kDa outer membrane protein was required for complementation. The amino acid sequence deduced from the nucleotide sequence showed extensive homology to PCPHi, an outer membrane lipoprotein of Haemophilus influenzae. We therefore termed this protein PCPYe. Plasmid-encoded pcpY mediated a low-affinity uptake of ferrioxamine B which may be caused by changes in the permeability of the outer membrane due to an overexpression of this outer membrane protein. A transposon insertion mutant in the plasmid-encoded pcpY gene was transferred into the chromosome of Y. enterocolitica. The resulting mutation had no effect on the high-affinity uptake of ferrioxamine B in Yersinia cells. Using the antibiotic ferrimycin we were able to isolate a Y. enterocolitica mutant lacking the high-affinity outer membrane receptor for ferrioxamine uptake, termed FoxA.