Evidence for direct regulation of diphtheria toxin gene transcription by an Fe2+-dependent DNA-binding repressor, DtoxR, in Corynebacterium diphtheriae.
Previous studies provided indirect evidence that in Corynebacterium diphtheriae regulation of diphtheria toxin gene (tox) transcription by iron is mediated by a bacterial repressor. By performing in vitro protein-DNA binding experiments, we establish that a corynebacterial Fe2+-sensitive protein, named DtoxR, can bind to a palindromic motif present in the tox promoter region. Binding of this factor prevents the interaction of the transcription initiation machinery with presumptive critical promoter elements, providing evidence that DtoxR is responsible for the repression of toxinogenesis observed in iron-containing growth medium.
Fourel
G
G
Unité d'Immunogénétique, Institut National de la Santé et de la Recherche Scientifique U276, Paris, France.
Phalipon
A
A
Kaczorek
M
M
D001667:Binding, Competitive; D002352:Carrier Proteins / Q000502:physiology; D003353:Corynebacterium diphtheriae / Q000235:genetics* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology*; D004167:Diphtheria Toxin / Q000235:genetics*; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D007501:Iron / Q000502:physiology*; D033862:Iron-Binding Proteins; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D033863:Transferrin-Binding Proteins
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D004167:Diphtheria Toxin; D033862:Iron-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D033863:Transferrin-Binding Proteins; D007501:Iron