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Updated: Jul 14, 2026
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Imaging of mtHyPer7, a Ratiometric Biosensor for Mitochondrial Peroxide, in Living Yeast Cells
Published on: June 2, 2023
A complex thiolate switch regulates the Bacillus subtilis organic peroxide sensor OhrR.
Jin-Won Lee1, Sumarin Soonsanga, John D Helmann
1Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA.
Summary
Oxidation of Bacillus subtilis OhrR, a peroxide sensor, forms a sulfenic acid intermediate. Further reactions creating S-thiolation or sulfenamide are crucial for gene derepression and protein regeneration.
Area of Science:
- Biochemistry
- Molecular Biology
- Redox Biology
Background:
- Protein thiolate oxidation is key in cellular redox regulation.
- Bacillus subtilis OhrR is an organic peroxide sensor regulating OhrA expression.
- Understanding OhrR oxidation mechanisms is vital for redox signaling pathways.
Purpose of the Study:
- To investigate the oxidation states of Bacillus subtilis OhrR.
- To determine the role of OhrR oxidation intermediates in gene regulation.
- To identify the products of OhrR oxidation and their functional significance.
Main Methods:
- Oxidation of purified OhrR protein.
- Characterization of OhrR oxidation products using mass spectrometry.
- Analysis of DNA-binding activity of OhrR intermediates.
- In vivo studies in Bacillus subtilis.
Main Results:
- OhrR oxidation yields a sulfenic acid intermediate that retains DNA-binding activity.
- Further oxidation leads to S-thiolation or sulfenamide formation, essential for derepression.
- S-thiolation protects OhrR from overoxidation and facilitates regeneration.
- Three distinct S-thiolated species were identified in vivo, including mixed disulfides with cysteine and CoASH.
- Evidence for in vivo sulfenamide formation was observed.
Conclusions:
- OhrR oxidation involves a sulfenic acid intermediate followed by S-thiolation or sulfenamide formation.
- These modifications are critical for derepression of OhrA and cellular peroxide response.
- S-thiolation serves as a protective mechanism and enables efficient regeneration of active OhrR.
- The study reveals novel in vivo oxidation pathways for OhrR in Bacillus subtilis.
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