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TrmB-like family transcription factor OxsR regulates the oxidative stress response in Haloferax volcanii

ABSTRACT: Haloarchaea tolerate high levels of reactive species that are naturally present in hypersaline environments. Hundreds of sRNAs, transcripts, and proteins are found altered in abundance when haloarchaea are exposed to reactive species, yet the regulators that control these responses are not well characterized. Here we report the function of Haloferax volcanii OxsR (redox stress responsive regulator, HVO_2970), a standalone winged-helix DNA binding domain protein of the TrmB-like family. Here we demonstrate that OxsR is important for growth in the presence of hypochlorite and binds specific regions of genomic DNA during hypochlorite stress by ChIP-seq analysis. The OxsR-bound intergenic regions were located nearby operons encoding oxidative stress functions, including the biosynthesis of low molecular weight thiols and thiol relay systems. Further analysis by qRT-PCR revealed that OxsR functions during oxidative stress largely as a transcriptional activator, and occasionally as a repressor. The conserved cysteine residue (C24) of OxsR and a CG-rich binding motif upstream of BRE/TATA box promoter elements were found important in the transcriptional activation of select operons during hypochlorite stress. 3D-modeling of OxsR revealed C24 to be located at a homodimer interface formed by antiparallel α1 helices, suggesting that C24 forms an intersubunit disulfide bond in the presence of oxidant that stabilizes the homodimer. The phylogenetic distribution of OxsR homologs with the conserved cysteine suggests this type of redox signaling mechanism is widespread in Archaea.

ORGANISM(S): Haloferax volcanii

PROVIDER: GSE196894 | GEO | 2022/02/18

REPOSITORIES: GEO

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