The Global Transcriptional Response ofBacillus subtilisto Peroxide Stress Is Coordinated by Three Transcription Factors

Abstract

Bacillus subtilis exhibits a complex adaptive response to low levels of peroxides. We used global transcriptional profiling to monitor the magnitude and kinetics of changes in the mRNA population after exposure to either hydrogen peroxide (H 2 O 2 ) or tert-butyl peroxide (t-buOOH). The peroxide stimulons could be largely accounted for by three regulons controlled by the PerR, B , and OhrR transcription factors. Three members of the PerR regulon (katA, mrgA, and zosA) were strongly induced by H 2 O 2 and weakly induced by t-buOOH. The remaining members of the PerR regulon were only modestly up-regulated by peroxide treatment. Overall, the magnitude of peroxide induction of PerR regulon genes corresponded well with the extent of derepression in a perR mutant strain. The B regulon was activated by 58 M H 2 O 2 but not by 8 M H 2 O 2 and was strongly activated by either t-buOOH or, in a control experiment, tert-butyl alcohol. Apart from the B regulon there was a single gene, ohrA, that was strongly and rapidly induced by t-buOOH exposure. This gene, controlled by the peroxide-sensing repressor OhrR, was not induced by any of the other conditions tested.

Defining the structure of the general stress regulon of Bacillus subtilis using targeted microarray analysis and random forest classification

“…3). On the other hand, oxidative stress has only minor importance in the classification of SigB dependence, which corresponds with reports proposing that oxidative stress likely induces only a core set of the SigB regulon (Helmann et al, 2003;Mostertz et al, 2004). The variable importance of the environmental stresses depending on the regulatory phosphatase RsbU was stronger than the variable importance calculated for RsbP-dependent energy stresses (Fig.…”

“…For the assessment of the gene expression pattern during low-temperature growth at 15 u C, samples were taken during mid-exponential growth at OD 540 0.9 and 1.0. In the design of the study we specifically reused stress imposition schemes that had already been reported previously (Antelmann et al, 1996;Helmann et al, 2003; Völker et al, 1995), and decided for environmental stresses to use intermediate stimulus strength that did not completely prevent growth. A graphical representation of the experimental setup with the stress conditions and time points investigated is provided in Supplementary Fig.…”

Cellular Defenses against Superoxide and Hydrogen Peroxide

“…One wonders, then, whether glutaredoxins and thioredoxins are actually needed only when H 2 O 2 stress is of such long duration as to compensate for the sluggish reactivity of protein thiols; whether they repair a small cohort of extremely reactive thiolate enzymes that have so far escaped detection; whether thiolate oxidations are primarily driven by reactions with oxygen or hydroxyl radicals, rather than H 2 O 2 ; or whether disulfide stress arises in natural environments from a different types of stressor, mimicked by thiol agents such as diamide. In fact, many bacteria-including Bacillus, Mycobacteria, Rhodobacter, and Streptomyces-do not include glutaredoxins or thioredoxins in their H 2 O 2 -inducible regulons (123)(124)(125). Instead, for example, Streptomyces controls synthesis of its thioredoxins with an anti-sigma factor protein that is activated when sulfur exchange reactions create a disulfide bond (126); notably, this system is easily triggered by diamide but requires millimolar doses of H 2 O 2 .…”

Physiological homogeneity among the endosymbionts of Riftia pachyptila and Tevnia jerichonana revealed by proteogenomics

“…reductase (TrxB, ratio 2.3), a component of the thiol/ disulfide redox system, might also be part of the oxidative stress response in Riftia symbiont cells as observed for other bacteria (Helmann et al, 2003;Ballal and Manna, 2010). These results suggest that the in situ oxygen concentrations in the Riftia trophosome were slightly higher than those in the Tevnia trophosome, which would be in line with the habitat chemistry measurements (see above and Table 1) that indicated a higher proportion of oxygen-rich sea water in the immediate surroundings of the Riftia plumes compared with the vent fluid surrounding the Tevnia plumes.…”