title: Aerobactin iron transport genes commonly encoded by certain ColV plasmids occur in the chromosome of a human invasive strain of Escherichia coli K1.
abstract: The aerobactin-mediated iron uptake system encoded by pColV-K30 and other ColV plasmids has been associated with the ability of Escherichia coli strains to cause disease. We investigated whether the pColV-K30 aerobactin system is present in E. coli K1 VW187 isolated from a human neonate with meningitis. This strain exhibited a functional aerobactin-mediated iron uptake system, as assessed by a cross-feeding bioassay and by its sensitivity to cloacin, a bacteriocin that recognizes the outer membrane receptor for iron-aerobactin complexes. By using a variety of techniques, we could not find any plasmid harboring the aerobactin genes. Hybridization of restriction endonuclease-cleaved chromosomal DNA from strain VW187 with various clones containing subsets of the pColV-K30 aerobactin region showed that the aerobactin genes were located on a 10.5-kilobase-pair chromosomal HindIII restriction fragment which also contained IS1-like insertion sequences. The chromosomal aerobactin region showed a high degree of conservation when compared with the homologous region in plasmid pColV-K30, although it was located on a different restriction endonuclease site environment.
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D003086:Bacteriocin Plasmids; D002876:Chromosomes, Bacterial / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity*; D005798:Genes, Bacterial; D008040:Genetic Linkage; D006801:Humans; D006877:Hydroxamic Acids; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents; D011971:Receptors, Immunologic / Q000235:genetics*; D017262:Siderophores
chemical_list: D001425:Bacterial Outer Membrane Proteins; D006877:Hydroxamic Acids; D007502:Iron Chelating Agents; D011971:Receptors, Immunologic; D017262:Siderophores; C034506:aerobactin receptor; C031819:aerobactin; D007501:Iron