Absence of DNA sequence homology with genes of the Escherichia coli hemB locus in Shiga-toxin producing E. coli (STEC) O157 strains.
By molecular cloning of chromosomal DNA of a human faecal Escherichia coli O6:non-motile strain, we identified a 1350-bp DNA segment which is commonly present in laboratory and wild-type E. coli strains but had no homology to DNA of Shiga-toxin producing E. coli O157, O145 and enteropathogens E. coli O55 strains. The nucleotide sequence of the 1350-bp segment cloned on plasmid pEO67 was determined (GenBank accession number AF087670) and a 97.2% sequence homology was found to a region of the E. coli hemB locus with an unknown gene function. The introduction of pEO67 into an STEC O157:H- strain had a stimulating effect on the growth of the recipient strain which was most expressed when bacteria were grown in iron depleted M9 medium with hemin added as the exogenous iron source. This growth effect was not observed with E. coli K-12 carrying pEO67. We suggest that the cloned gene is involved in iron uptake of E. coli and that the alteration in this part of the hemB locus is clonally inherited in genetically closely related STEC O157 and O55 strains.
Stümpfle
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P
Robert Koch-Institut, Division of Emerging Bacterial Pathogens, Berlin, Germany.
Broll
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H
Beutin
L
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D001427:Bacterial Toxins / Q000096:biosynthesis*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D005798:Genes, Bacterial; D006461:Hemolysis; D008969:Molecular Sequence Data; D019081:O Antigens; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012703:Serotyping; D022603:Shiga Toxins
D001427:Bacterial Toxins; D004269:DNA, Bacterial; D019081:O Antigens; D022603:Shiga Toxins