IscR-dependent gene expression links iron-sulphur cluster assembly to the control of O2-regulated genes in Escherichia coli

Mol Microbiol. 2006 May;60(4):1058-75. doi: 10.1111/j.1365-2958.2006.05160.x.


IscR is an iron-sulphur (Fe-S) cluster-containing transcription factor that represses transcription of the operon containing its own gene and the iscSUA-hscBA-fdx genes, whose products are involved in Fe-S cluster biogenesis. In this study, global transcriptional profiling of Escherichia coli IscR(+) and IscR(-) strains grown under aerobic and anaerobic conditions indicated that 40 genes in 20 predicted operons were regulated by IscR. DNase I footprinting and/or in vitro transcription reactions identified seven new promoters under direct IscR control. Among these were genes encoding known or proposed functions in Fe-S cluster biogenesis (sufABCDSE, yadR and yhgI) and Fe-S cluster-containing anaerobic respiratory enzymes (hyaABCDEF, hybOABCDEFG and napFDAGHBC). The finding that IscR repressed expression of the hyaA, hybO and napF promoters specifically under aerobic growth conditions suggests a new mechanism to explain their upregulation under anaerobic growth conditions. Phylogenetic footprinting of the DNase I protected regions of seven promoters implies that there are at least two different classes of IscR binding sites conserved among many bacteria. The findings presented here indicate a more general role of IscR in the regulation of Fe-S cluster biogenesis and that IscR contributes to the O(2) regulation of several promoters controlling the expression of anaerobic Fe-S proteins.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaerobiosis / genetics
  • Base Sequence
  • Escherichia coli / genetics*
  • Escherichia coli / physiology
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Genes, Bacterial / genetics
  • Iron-Sulfur Proteins / genetics*
  • Molecular Sequence Data
  • Multigene Family / genetics
  • Oxidative Stress / genetics
  • Oxygen / physiology*
  • Promoter Regions, Genetic / genetics
  • Superoxide Dismutase / genetics
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • Escherichia coli Proteins
  • Iron-Sulfur Proteins
  • IscR protein, E coli
  • Transcription Factors
  • Superoxide Dismutase
  • Oxygen