IroN, a novel outer membrane siderophore receptor characteristic of Salmonella enterica

Andreas J. Bäumler, Tracy L. Norris, Todd Lasco, Wolfgang Voigt, Rolf Reissbrodt, Wolfgang Rabsch, Fred Heffron

    Research output: Contribution to journalArticlepeer-review

    117 Scopus citations


    Speciation in enterobacteria involved horizontal gene transfer. Therefore, analysis of genes acquired by horizontal transfer that are present in one species but not its close relatives is expected to give insights into how new bacterial species were formed. In this study we characterize iroN, a gene located downstream of the iroBC operon in the iroA locus of Salmonella enterica serotype Typhi. Like iroBC, the iron gene is present in all phylogenetic lineages of S. enterica but is absent from closely related species such as Salmonella bongori or Escherichia coli. Comparison of the deduced amino acid sequence of iron with other proteins suggested that this gene encodes an outer membrane siderophore receptor protein. Mutational analysis in S. enterica and expression in E. coli identified a 78-kDa outer membrane protein as the iron gene product. When introduced into an E. coli fepA cir fiu aroB mutant on a cosmid, iroN mediated utilization of structurally related catecholate siderophores, including N-(2,3- dihydroxybenzoyl)-L-serine, myxochelin A, benzaldehyde-2,3- dihydroxybenzhydrazone, 2-N,6-N-bis(2,3-dihydroxybenzoyl)-L-lysine, 2-N,6-N- bis(2,3-dihydroxybenzoyl)-L-lysine amide, and enterochelin. These results suggest that the iroA locus functions in iron acquisition in S. enterica.

    Original languageEnglish (US)
    Pages (from-to)1446-1453
    Number of pages8
    JournalJournal of bacteriology
    Issue number6
    StatePublished - Mar 1998

    ASJC Scopus subject areas

    • Microbiology
    • Molecular Biology


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