An ideR mutant of Mycobacterium smegmatis has derepressed siderophore production and an altered oxidative-stress response.
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.
Dussurget
O
O
Department of Microbiology, Public Health Research Institute, New York, New York 10016, USA.
Rodriguez
M
M
Smith
I
I
D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D015153:Blotting, Western; D002374:Catalase / Q000096:biosynthesis; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005290:Ferric Compounds / Q000138:chemical synthesis / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D009161:Mycobacterium / Q000235:genetics*; D010080:Oxazoles / Q000378:metabolism; D018384:Oxidative Stress / Q000235:genetics*; D010456:Peptides, Cyclic / Q000096:biosynthesis / Q000138:chemical synthesis; D009195:Peroxidase / Q000096:biosynthesis; D010957:Plasmids; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D017262:Siderophores / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis; D014170:Transformation, Genetic
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D005290:Ferric Compounds; C096348:IdeR protein, Mycobacterium tuberculosis; D010080:Oxazoles; D010456:Peptides, Cyclic; D012097:Repressor Proteins; D017262:Siderophores; C016451:ferriexochelin; C018608:mycobactins; D006861:Hydrogen Peroxide; D007501:Iron; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase