AN ABC TRANSPORTER SYSTEM OF YERSINIA-PESTIS ALLOWS UTILIZATION OF CHELATED IRON BY ESCHERICHIA-COLI SAB11

The acquisition of iron is an essential component in the pathogenesis of Yersinia pestis, the agent of bubonic and pneumonic plague, A cosmi d library derived from the genomic DNA of Y. pestis KIM6+ was used for transduction of an Escherichia coli mutant (SAB11) defective in the b iosynthesis of the siderophore enterobactin. Recombinant plasmids whic h had a common 13-kb BamHI fragment were isolated from SAB11 transduct ants in which growth but not enterobactin synthesis was restored on me dia containing the iron chelator EDDA [ethylenediamine-di(o-hydroxyphe nyl acetic acid)], Subcloning and transposon mutagenesis revealed a 5. 6-kb region, designated yfe, essential for SAB11 growth stimulation, I n vitro transcription-translation analysis identified polypeptides of 18, 29.5, 32, and 33 kDa encoded by the yfe locus, Sequence analysis s hows this locus to be comprised of five genes in two separate operons which have potential Fur-binding sequences in both promoters, A putati ve polycistronic operon, yfeABCD, is Fur regulated and responds to iro n and manganese, A functional Fur protein is required for the observed manganese repression of this operon. This operon encodes polypeptides which have strong similarity to the ATP-binding cassette (ABC) family of transporters and include a periplasmic binding protein (YfeA), an ATP-binding protein (YfeB), and two integral membrane proteins (YfeC a nd -D), which likely function in the acquisition of inorganic iron and possibly other ions. The similar to 21-kDa protein encoded by the sep arately transcribed yfeE gene may be located in the cell envelope, sin ce a yfeE::TnphoA fusion is PhoA(+). Mutations in this gene abrogate g rowth of SAB11 on iron chelated media.