Expression of the Escherichia coli IrgA homolog adhesin is regulated by the ferric uptake regulation protein

Microb Pathog. 2006 Dec;41(6):207-17. doi: 10.1016/j.micpath.2006.07.006. Epub 2006 Sep 6.


The IrgA homolog adhesin (Iha) is an adherence-conferring outer membrane protein of Escherichia coli associated with enterohemorrhagic and uropathogenic strains. Here, we used primer extension analysis to identify iha promoters in O157:H7 and uropathogenic E. coli strains. Transcriptional fusions demonstrated that iha transcription is repressed by iron. Gel shifts using purified ferric uptake regulator protein (Fur) demonstrated that repression involves a direct interaction between Fur and the iha promoter. We identified strain-dependent differences in iha expression and determined that single nucleotide polymorphisms upstream of the iha promoter, in particular position -85, contribute to differences in expression levels.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adhesins, Escherichia coli / biosynthesis
  • Adhesins, Escherichia coli / genetics
  • Adhesins, Escherichia coli / physiology*
  • Bacterial Adhesion / physiology
  • Bacterial Proteins / physiology*
  • Base Sequence
  • Escherichia coli O157 / genetics
  • Escherichia coli O157 / metabolism
  • Escherichia coli O157 / physiology*
  • Ferric Compounds / pharmacology*
  • Gene Expression Regulation, Bacterial / drug effects
  • Molecular Sequence Data
  • Polymorphism, Single Nucleotide
  • Promoter Regions, Genetic
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / genetics
  • Repressor Proteins / physiology*
  • Single-Strand Specific DNA and RNA Endonucleases / metabolism
  • Transcription, Genetic / physiology


  • Adhesins, Escherichia coli
  • Bacterial Proteins
  • Ferric Compounds
  • RNA, Bacterial
  • Repressor Proteins
  • ferric uptake regulating proteins, bacterial
  • Single-Strand Specific DNA and RNA Endonucleases