Iron, DtxR, and the regulation of diphtheria toxin expression

Mol Microbiol. 1994 Oct;14(2):191-7. doi: 10.1111/j.1365-2958.1994.tb01280.x.


In recent years considerable advances have been made in the understanding of the molecular basis of iron-mediated regulation of diphtheria toxin expression. The tox gene has been shown to be regulated by the heavy metal ion-activated regulatory element DtxR. In the presence of divalent heavy metal ions, DtxR becomes activated and binds to a 9 bp interrupted palindromic sequence. The consensus-binding site has been determined by both the sequence analysis of DtxR-responsive operators cloned from genomic libraries of Corynebacterium diphtheriae as well as by in vitro genetic methods using cyclic amplification of selected targets (CASTing). It is now clear that DtxR functions as a global iron-sensitive regulatory element in the control of gene expression in C. diphtheriae. In addition, the metal ion-activation domain of DtxR is being characterized by both mutational analysis and determination of the X-ray structure at 3.0 A resolution.

Publication types

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

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Binding Sites
  • Cloning, Molecular
  • Corynebacterium diphtheriae / genetics*
  • Corynebacterium diphtheriae / growth & development
  • Corynebacterium diphtheriae / metabolism
  • DNA, Bacterial / metabolism*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Diphtheria Toxin / biosynthesis
  • Diphtheria Toxin / genetics*
  • Gene Expression Regulation, Bacterial*
  • Genes, Bacterial
  • Iron / metabolism*
  • Molecular Sequence Data
  • Operator Regions, Genetic


  • Bacterial Proteins
  • DNA, Bacterial
  • DNA-Binding Proteins
  • Diphtheria Toxin
  • DtxR protein, Corynebacterium diphtheriae
  • Iron