Bacillus subtilis contains multiple Fur homologues: identification of the iron uptake (Fur) and peroxide regulon (PerR) repressors.
Fur (ferric uptake regulator) proteins control iron uptake in many Gram-negative bacteria. Although Fur homologues have been identified in Gram-positive bacteria, their roles in gene regulation are unknown. Genome sequencing has revealed three fur homologues in Bacillus subtilis: yqkL, yqfV and ygaG. We demonstrate that yqkL encodes an iron uptake repressor: both siderophore biosynthesis and transcription of ferri-siderophore uptake genes is constitutive in the yqkL mutant. Thus, yqkL encodes a repressor that is functionally as well as structurally related to Fur. B. subtilis peroxide stress genes are induced by either H2O2 or by metal ion limitation. Previous genetic studies defined a regulatory locus, perR, postulated to encode the peroxide regulon repressor. We demonstrate that a ygaG mutant has the perR phenotype: It is highly resistant to peroxides and overexpresses catalase, alkyl hydroperoxide reductase and the DNA binding protein MrgA. Nine spontaneous perR mutations, isolated by virtue of their ability to derepress mrgA transcription in the presence of managanous ion, all contain sequence changes in the ygaG locus and can be complemented by the cloned ygaG gene. Thus, ygaG encodes the peroxide regulon repressor and is allelic with perR.
Section of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA.
N
N
Bsat
A
A
Herbig
L
L
Casillas-Martinez
P
P
Setlow
J D
JD
Helmann
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D062385:Hydroxybenzoates / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010545:Peroxides / Q000378:metabolism*; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D062385:Hydroxybenzoates; D010545:Peroxides; D012097:Repressor Proteins; D017262:Siderophores; C068477:ferric uptake regulating proteins, bacterial; C009135:2,3-dihydroxybenzoic acid; D007501:Iron