Transcriptional control of the iron-responsive fxbA gene by the mycobacterial regulator IdeR

Olivier Dussurget, Juliano Timm, Manuel Gomez, Benjamin Gold, Shengwei Yu, Sue Z. Sabol, Randall K. Holmes, William R. Jacobs, Issar Smith

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


Exochelin is the primary extracellular siderophore of Mycobacterium smegmatis, and the iron-regulated fxbA gene encodes a putative formyltransferase, an essential enzyme in the exochelin biosynthetic pathway (E. H. Fiss, Y. Yu, and W. R. Jacobs, Jr., Mol. Microbiol. 14:557-569, 1994). We investigated the regulation of fxbA by the mycobacterial IdeR, a homolog of the Corynebacterium diphtheriae iron regulator DtxR (M.P. Schmitt, M. Predich, L. Doukhan, I. Smith, and R. K. Holmes, Infect. Immun. 63:4284- 4289, 1995). Gel mobility shift experiments showed that IdeR binds to the fxbA regulatory region in the presence of divalent metals. DNase I footprinting assays indicated that IdeR binding protects a 28-bp region containing a palindromic sequence of the fxbA promoter that was identified in primer extension assays, fxbA regulation was measured in M. smegmatis wild- type and ideR mutant strains containing fxbA promoter-lacZ fusions. These experiments confirmed that fxbA expression is negatively regulated by iron and showed that inactivation of ideR results in iron-independent expression of fxbA. However, the levels of its expression in the ideR mutant were approximately 50% lower than those in the wild-type strain under iron limitation, indicating an undefined positive role of IdeR in the regulation of fxbA.

Original languageEnglish (US)
Pages (from-to)3402-3408
Number of pages7
JournalJournal of Bacteriology
Issue number11
StatePublished - Jun 1999

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


Dive into the research topics of 'Transcriptional control of the iron-responsive fxbA gene by the mycobacterial regulator IdeR'. Together they form a unique fingerprint.

Cite this