Advertisement

An ideR mutant of Mycobacterium smegmatis has derepressed siderophore production and an altered oxidative-stress response

Authors

  • Olivier Dussurget,

    1. Department of Microbiology, The Public Health Research Institute, 455 First Avenue, New York, New York 10016, USA.
    2. UFR de Biochimie, Université Paris 7, 75251 Paris Cedex 05, France.
    Search for more papers by this author
  • Marcela Rodriguez,

    1. Department of Microbiology, The Public Health Research Institute, 455 First Avenue, New York, New York 10016, USA.
    2. Department of Microbiology, New York University Medical Centre, New York, New York 10016, USA.
    Search for more papers by this author
  • Issar Smith

    1. Department of Microbiology, The Public Health Research Institute, 455 First Avenue, New York, New York 10016, USA.
    2. Department of Microbiology, New York University Medical Centre, New York, New York 10016, USA.
    Search for more papers by this author

Issar Smith E-mail smitty@phri.nyu.edu; Tel. (212) 578 0867; Fax (212) 578 0804.

Abstract

The mycobacterial IdeR protein is a homologue of the diphtheria-toxin repressor DtxR. We have previously demonstrated that Mycobacterium tuberculosis IdeR, like DtxR, represses transcription of Corynebacterium diphtheriae iron-regulated promoters in vivo and binds to C. diphtheriae operators in a metal-dependent manner in vitro. We show here that ideR mutants of M. smegmatis, constructed by allelic replacement, were defective in their ability to repress siderophore biosynthesis in the presence of iron. They were also more sensitive to hydrogen peroxide and had decreased levels of catalase/peroxidase (KatG) and manganese superoxide dismutase (Mn-SOD). This indicates that IdeR is a negative regulator of siderophore production and is required for the response to superoxide- and hydrogen peroxide stress. We propose that IdeR is the mycobacterial counterpart of the Escherichia coli Fur protein, i.e. it is a pleiotropic regulator that couples iron metabolism to the oxidative-stress response.

Ancillary