Determining the association of the TrmB‐like protein OxsR to chromatin binding and oxidative stress in Haloferax volcanii

Abstract

Archaea are single‐celled microorganisms that are well known for their ability to survive and thrive in harsh environmental conditions; however, the factors that mediate homeostasis during redox and/or oxidative stress are not fully understood this domain of life. OxsR (redox stress responsive regulator, HVO_2970) is a TrmB‐like protein of arCOG002242 that is increased several‐fold in abundance during hypochlorite stress based on quantitative proteomic analysis of the halophilic archaeon Haloferax volcanii. TrmB (transcription regulator of mal operon) family proteins are typically transcription factors that bind sugar/effector molecules and regulate the expression of carbon metabolism and transport genes. OxsR has a winged‐helix DNA binding domain but lacks the sugar/effector binding domain common to members of the TrmB family. Here we find that OxsR has a conserved cysteine residue (C24) at a predicted homodimer interface that may to be intimately associated with redox homeostasis in this archaeon. OxsR is required: i) for tolerance to oxidative stress and ii) for an increase in the level of transcripts associated with DNA repair and oxidative stress response. Current work is focused on determining how OxsR senses redox stress, binds DNA, and regulates transcript levels by use of RNAseq, ChIP‐Seq and ChIP‐PCR methods. To this end, we have prepared an RNA library for RNAseq analysis and integrated a C‐terminal hemagglutinin (HA) tag onto the oxsR gene locus for the ChIP methods. Overall, OxsR is an apparent redox sensor required for elevated transcript levels of DNA repair and oxidative stress response pathways. The distribution of OxsR homologs with conserved cysteine residue(s) in Euryarchaeota and Crenarchaeota phyla suggests this type of redox sensor is widespread in Archaea.Support or Funding InformationFunds for this project were awarded to JM‐F through the Bilateral NSF/BIO‐BBSRC program (NSF 1642283), the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, Physical Biosciences Program (DOE DE‐FG02‐05ER15650) and the National Institutes of Health (NIH R01 GM57498).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.