The pathogen-associated iroA gene cluster mediates bacterial evasion of lipocalin 2 Academic Article uri icon


MeSH Major

  • Acute-Phase Proteins
  • Bacterial Outer Membrane Proteins
  • Escherichia coli
  • Membrane Fusion
  • Multigene Family
  • Oncogene Proteins


  • Numerous bacteria cope with the scarcity of iron in their microenvironment by synthesizing small iron-scavenging molecules known as siderophores. Mammals have evolved countermeasures to block siderophore-mediated iron acquisition as part of their innate immune response. Secreted lipocalin 2 (Lcn2) sequesters the Escherichia coli siderophore enterobactin (Ent), preventing E. coli from acquiring iron and protecting mammals from infection by E. coli. Here, we show that the iroA gene cluster, found in many pathogenic strains of Gram-negative enteric bacteria, including E. coli, Salmonella spp., and Klebsiella pneumoniae, allows bacteria to evade sequestration of Ent by Lcn2. We demonstrate that C-glucosylated derivatives of Ent produced by iroA-encoded enzymes do not bind purified Lcn2, and an iroA-harboring strain of E. coli is insensitive to the growth inhibitory effects of Lcn2 in vitro. Furthermore, we show that mice rapidly succumb to infection by an iroA-harboring strain of E. coli but not its wild-type counterpart, and that this increased virulence depends on evasion of host Lcn2. Our findings indicate that the iroA gene cluster allows bacteria to evade this component of the innate immune system, rejuvenating their Ent-mediated iron-acquisition pathway and playing an important role in their virulence.

publication date

  • October 31, 2006



  • Academic Article



  • eng

PubMed Central ID

  • PMC1637611

Digital Object Identifier (DOI)

  • 10.1073/pnas.0604636103

PubMed ID

  • 17060628

Additional Document Info

start page

  • 16502

end page

  • 7


  • 103


  • 44