Structure of the Shigella dysenteriae haem transport locus and its phylogenetic distribution in enteric bacteria

Elizabeth E. Wyckoff, Donald Duncan, Alfredo G. Torres, Melody Mills, Kamiel Maase, Shelley M. Payne

Research output: Contribution to journalArticle

102 Scopus citations

Abstract

The ability to transport and use haemin as an iron source is frequently observed in clinical isolates of Shigella spp. and pathogenic Escherichia coli. We found that many of these haem-utilizing E. coli strains contain a gene that hybridizes at high stringency to the S. dysenterlae type 1 haem receptor gene, shuA. These shuA-positive strains belong to multiple phylogenetic groups and include clinical isolates from enteric, urinary tract and systemic infections. The distribution of shuA in these strains suggests horizontal transfer of the haem transport locus. Some haemutilizing pathogenic E. coli strains did not hybridize with shuA, so at least one other haem transport system is present in this group. We also characterized the chromosomal region containing shuA in S. dysenteriae. The shuA gene is present in a discrete locus, designated the haem transport locus, containing eight open reading frames. Several of the proteins encoded in this locus participate with ShuA in haem transport, as a Salmonella typhimurium strain containing the entire haem transport locus used haem much more efficiently than the same strain containing only shuA. The haem transport locus is not present in E. coli K-12 strains, but the sequences flanking the haem transport locus in S. dysenteriae matched those at the 78.7 minute region of E. coli K-12. The junctions and flanking sequences in the shuA-positive pathogenic E. coli strains tested were nearly identical to those in S. dysenteriae, indicating that, in these strains, the haem transport locus has an organization similar to that in S. dysenteriae, and it is located in the same relative position on the chromosome.

Original languageEnglish (US)
Pages (from-to)1139-1152
Number of pages14
JournalMolecular Microbiology
Volume28
Issue number6
DOIs
StatePublished - Jul 8 1998
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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