Title : A monomeric peroxiredoxin plays dual role in Deinococcus radiodurans R1 and exhibits resistance against heat and oxidative stress
Abstract:
Peroxiredoxins are one of the enzymatic antioxidants that play a protective role against damage caused by reactive oxygen species (ROS). Deinococcus radiodurans R1 is a highly resistant bacterium against ionizing radiation and oxidative stress conditions. The phylogenetic analysis indicated that all the four putative peroxiredoxins (DR0846, DR1208, DR1209, and DR2242) in D. radiodurans belongs to PrxQ group which plays an important role in stress resistance. DR0846 was selected as a PrxQ candidate in this study on the basis of expression analysis in response to H2O2 and gamma radiation. AMS shift assay, size exclusion chromatography (SEC) and native-gel results corroborated that DR0846 exists in monomeric form with an intramolecular disulfide bond between the two cysteine residues. In this study, we found that DR0846 plays dual role by functioning as a molecular chaperone as well as a peroxidase. Site directed mutagenesis confirmed that both the cysteines are important for peroxidase activity. A double deletion mutant deficient in catalase DR1998 and peroxidase DR0846 exhibits sensitive phenotype to heat and oxidative stress as compared to single mutants and wild type cells. This study demonstrates that DR0846 is an important antioxidant enzyme with dual functions as it contributes to resistance against heat and oxidative stress in D. radiodurans.
