OxyR2 Functions as a Three-state Redox Switch to Tightly Regulate Production of Prx2, a Peroxiredoxin of Vibrio vulnificus.
The bacterial transcriptional regulator OxyR is known to function as a two-state redox switch. OxyR senses cellular levels of H2O2 via a "sensing cysteine" that switches from the reduced to a disulfide state upon H2O2 exposure, inducing the expression of antioxidant genes. The reduced and disulfide states of OxyR, respectively, bind to extended and compact regions of DNA, where the reduced state blocks and the oxidized state allows transcription and further induces target gene expression by interacting with RNA polymerase. Vibrio vulnificus OxyR2 senses H2O2 with high sensitivity and induces the gene encoding the antioxidant Prx2. In this study, we used mass spectrometry to identify a third redox state of OxyR2, in which the sensing cysteine was overoxidized to S-sulfonated cysteine (Cys-SO3H) by high H2O2 in vitro and in vivo, where the modification deterred the transcription of prx2 The DNA binding preferences of OxyR25CA-C206D, which mimics overoxidized OxyR2, suggested that overoxidized OxyR2 binds to the extended DNA site, masking the -35 region of the prx2 promoter. These combined results demonstrate that OxyR2 functions as a three-state redox switch to tightly regulate the expression of prx2, preventing futile production of Prx2 in cells exposed to high levels of H2O2 sufficient to inactivate Prx2. We further provide evidence that another OxyR homolog, OxyR1, displays similar three-state behavior, inviting further exploration of this phenomenon as a potentially general regulatory mechanism.
From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea.
Ye-Ji
YJ
Bang
From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea.
Zee-Won
ZW
Lee
From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea.
Dukyun
D
Kim
the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea.
Inseong
I
Jo
the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea hanc210@snu.ac.kr.
Nam-Chul
NC
Ha
From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea choish@snu.ac.kr.
Sang Ho
SH
Choi
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D041261:Vibrio vulnificus / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D014157:Transcription Factors; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D003545:Cysteine
OxyR; Vibrio vulnificus; antioxidant; gene regulation; hydrogen peroxide; overoxidation; peroxiredoxin; reactive oxygen species; sensing cysteine; three-state redox switch