Journal Article

OhsR acts as an organic peroxide-sensing transcriptional activator using an S-mycothiolation mechanism in Corynebacterium glutamicum

Liu, Jinfeng, Che, Chengchuan, Su, Tao, Li, GuiZhi, Gong, Zhijin, Chen, Can, Yang, Ge, Si, Meiru

2018

Overview

Background Corynebacterium glutamicum is a well-known producer of various l -amino acids in industry. During the fermenting process, C. glutamicum unavoidably encounters oxidative stress due to a specific reactive oxygen species (ROS) produced by consistent adverse conditions. To combat the ROS, C. glutamicum has developed many common disulfide bond-based regulatory devices to control a specific set of antioxidant genes. However, nothing is known about the mixed disulfide between the protein thiol groups and the mycothiol (MSH) ( S -mycothiolation)-based sensor. In addition, no OhrR (organic hydroperoxide resistance regulator) homologs and none of the organic hydroperoxide reductase (Ohr) sensors have been described in the alkyl hydroperoxide reductase CF-missing C. glutamicum, while organic hydroperoxides (OHPs)-specific Ohr was a core detoxification system. Results In this study, we showed that the C. glutamicum OhsR acted as an OHPs sensor that activated ohr expression. OhsR conferred resistance to cumene hydroperoxide (CHP) and t -butyl hydroperoxide but not H 2 O 2 , hypochlorous acid, and diamide; this outcome was substantiated by the fact that the ohsR -deficient mutant was sensitive to OHPs but not inorganic peroxides. The DNA binding activity of OhsR was specifically activated by CHP. Mutational analysis of the two cysteines (Cys125 and Cys261) showed that Cys125 was primarily responsible for the activation of DNA binding. The oxidation of Cys125 produced a sulfenic acid (C125-SOH) that subsequently reacted with MSH to generate S -mycothiolation that was required to activate the ohr expression. Therefore, OhsR regulated the ohr expression using an S -mycothiolation mechanism in vivo. Conclusion This is the first report demonstrating that the regulatory OhsR specifically sensed OHPs stress and responded to it by activating a specific ohr gene under its control using an S -mycothiolated mechanism.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Actinomycetales / Alkyl hydroperoxide reductase / Amino acids / Antioxidants / Applied Microbiology / Bacteria / Bacterial Proteins - metabolism / Binding / Biosensors / Biotechnology / Butyl hydroperoxide / C. glutamicum / Cell regulation / Chemical bonds / Chemistry / Chemistry and Materials Science / Corynebacterium glutamicum / Corynebacterium glutamicum - metabolism / Cumene / Cumene hydroperoxide / Deficient mutant / Deoxyribonucleic acid / Detoxification / DNA / DNA damage / E coli / Enzymes / Enzymology / Gene expression / Genetic aspects / Genetic Engineering / Homology / Hydrogen peroxide / Hypochlorous acid / Inorganic peroxides / Laboratories / MarR / Microbial Genetics and Genomics / Microbiology / Molecular weight / Mycothiol / Ohr gene / Organic hydroperoxide / Organic peroxide stress / Oxidation / Oxidative Stress / Peroxides / Properties / Proteins / Reactive oxygen species / S-mycothiolation / Sensors / Stress (Physiology) / Sulfenic acid / Transcription / Transcription factors / Transcription Factors - genetics / Transcription regulation / Tuberculosis