title: IroN, a novel outer membrane siderophore receptor characteristic of Salmonella enterica.
abstract: 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.
authors.affiliation: Department of Medical Microbiology and Immunology, Texas A&M University, College Station 77843-1114, USA. abaumler@tamu.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Bäumler
authors.forename: T L
authors.initials: TL
authors.lastname: Norris
authors.forename: T
authors.initials: T
authors.lastname: Lasco
authors.forename: W
authors.initials: W
authors.lastname: Voight
authors.forename: R
authors.initials: R
authors.lastname: Reissbrodt
authors.forename: W
authors.initials: W
authors.lastname: Rabsch
authors.forename: F
authors.initials: F
authors.lastname: Heffron
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins; D003001:Cloning, Molecular; D003360:Cosmids; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009876:Operon; D010802:Phylogeny; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism*; D011995:Recombination, Genetic; D015183:Restriction Mapping; D012475:Salmonella / Q000235:genetics / Q000378:metabolism; D019779:Salmonella enterica / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D017262:Siderophores / Q000378:metabolism; D013045:Species Specificity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D011956:Receptors, Cell Surface; D017262:Siderophores; C035902:siderophore receptors