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

112 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
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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