Coordinate regulation of siderophore and diphtheria toxin production by iron in Corynebacterium diphtheriae

Microb Pathog. 1990 Oct;9(4):267-73. doi: 10.1016/0882-4010(90)90015-i.


Iron is an environmental signal which regulates the coordinate expression of genes associated with virulence in many pathogenic bacteria. In response to iron-deprivation, lysogenic Corynebacterium diphtheriae C7 (beta) synthesizes and secretes diphtheria toxin and siderophore and induces a high-affinity iron uptake system. Diphtheria toxin is encoded by beta phage, but genes for siderophore production are encoded on the bacterial chromosome. Diphtheria toxin and siderophore production were shown to be coordinately induced during late logarithmic phase growth of wild-type C7(beta) in iron-limited medium. C. diphtheriae mutant C7hm723 produced siderophore and toxin constitutively under low-iron and high-iron conditions, but in mutants HC1, HC3, HC4, and HC5 their synthesis was partially repressed under high-iron conditions. The phenotypes of HC1, HC3, HC4, and HC5 are consistent with their severe defects in iron uptake, but the phenotype of C7hm723 is more likely to be explained by inactivation of the repressor for the iron regulon of C. diphtheriae.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cetrimonium
  • Cetrimonium Compounds
  • Corynebacterium diphtheriae / genetics*
  • Corynebacterium diphtheriae / pathogenicity
  • Diphtheria Toxin / biosynthesis
  • Diphtheria Toxin / genetics*
  • Edetic Acid / pharmacology
  • Gene Expression Regulation, Bacterial / drug effects*
  • Hydroxybenzoates / analysis*
  • Iron / pharmacology*
  • Iron Chelating Agents / metabolism*
  • Piperazines
  • Promoter Regions, Genetic
  • Repressor Proteins / drug effects*
  • Siderophores
  • Virulence


  • Cetrimonium Compounds
  • Diphtheria Toxin
  • Hydroxybenzoates
  • Iron Chelating Agents
  • Piperazines
  • Repressor Proteins
  • Siderophores
  • chrome azurol S
  • EDDA
  • Edetic Acid
  • Iron
  • Cetrimonium