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Bacillus subtilis contains multiple Fur homologues: identification of the iron uptake (Fur) and peroxide regulon (PerR) repressors
Author(s) -
Bsat Nada,
Herbig Andrew,
CasillasMartinez Lilliam,
Setlow Peter,
Helmann John D.
Publication year - 1998
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1998.00921.x
Subject(s) - regulon , repressor , biology , bacillus subtilis , genetics , gene , mutant , tetr , biochemistry , transcription factor , bacteria
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 H 2 O 2 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 manganous 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 .