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Knockout of pprM Decreases Resistance to Desiccation and Oxidation in Deinococcus radiodurans.

ABSTRACT: Deinococcus radiodurans has attracted a great interest in the past decades due to its extraordinary resistance to ionizing radiation and highly efficient DNA repair system. Recent studies indicated that pprM is a putative pleiotropic gene in D. radiodurans and plays an important role in radioresistance and antioxidation, but its underlying mechanisms are poorly elucidated. In this study, pprM mutation was generated to investigate resistance to desiccation and oxidative stress. The result showed that the survival of pprM mutant under desiccation was markedly retarded compared to the wild strain from day 7-28. Furthermore, knockout of pprM increases the intercellular accumulation of ROS and the sensibility to H₂O₂ stress in the bacterial growth inhibition assay. The absorbance spectrum experiment for detecting the carotenoid showed that deinoxanthin, a carotenoid that peculiarly exists in Deinococcus, was reduced in the pprM mutant in the pprM mutant. Quantitative real time PCR showed decreased expression of three genes viz. CrtI (DR0861, 50%),CrtB (DR0862, 40%) and CrtO (DR0093, 50%), which are involved in deinoxanthin synthesis, and of Dps (DNA protection during starving) gene (DRB0092) relevant to ion combining and DNA protection in cells. Our results suggest that pprM may affect antioxidative ability of D. radiodurans by regulating the synthesis of deinoxanthin and the concentration of metal ions. This may provide new clues for the treatment of antioxidants.

SUBMITTER: Zeng Y

PROVIDER: S-EPMC5574771 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Knockout of pprM Decreases Resistance to Desiccation and Oxidation in Deinococcus radiodurans.

Zeng Yang Y Ma Yun Y Xiao Fangzhu F Wang Wuzhou W He Shuya S

Indian journal of microbiology 20170610 3

Deinococcus radiodurans has attracted a great interest in the past decades due to its extraordinary resistance to ionizing radiation and highly efficient DNA repair system. Recent studies indicated that pprM is a putative pleiotropic gene in D. radiodurans and plays an important role in radioresistance and antioxidation, but its underlying mechanisms are poorly elucidated. In this study, pprM mutation was generated to investigate resistance to desiccation and oxidativ ...[more]

PMID: 28904416

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Project description:Deinococcus radiodurans known for its extraordinary resistance to ionizing radiation contains bacterial phytochrome (BphP), a member of the family of red/far-red light-sensing proteins. In this study, we constructed a bphP mutant strain (ΔbphP) to investigate the role of D. radiodurans BphP (DrBphP) in the DNA damage response. When cells were incubated under light and dark conditions following exposure to DNA damaging agents, such as γ- and UV-radiation and mitomycin C (MMC), no significant difference in cell survival was observed between the wild-type D. radiodurans strain (WT) and ΔbphP. However, when continuously exposed to MMC under light conditions, the WT strain notably exhibited increased survival compared to cells grown in the dark. The increased survival was not observed in the ΔbphP strain. These results are indicative of the protective role of light-activated DrBphP in the presence of MMC. Site-directed mutagenesis revealed that the conserved amino acids Cys-24 and His-532 involved in chromophore binding and signal transduction, respectively, were essential for the protective function of DrBphP. Inactivation of the cognate response regulator (RR; DrBphR) of DrBphP increased MMC resistance in the dark. In trans complementation of the bphP bphR double mutant strain (ΔbphPR) with DrBphR decreased MMC resistance. Considering that DrBphP acts as a light-activated phosphatase that dephosphorylates DrBphR, it appears that phosphorylated DrBphR exerts a negative effect on cell survival in the presence of MMC. DrBphP overexpression resulted in an increase in MMC resistance of ΔbphPR, implying that other RRs might be involved in the DrBphP-mediated signaling pathway. A mutant lacking the dr_0781 gene (Δdr_0781) demonstrated the same MMC phenotype as ΔbphR. Survival was further increased in the bphR dr_0781 double mutant strain compared to each single mutant ΔbphR or Δdr_0781, suggesting that DR_0781 is also involved in the DrBphP-dependent MMC sensitivity. This study uncovered a previously unknown phenomenon of red/far-red light-dependent DNA damage survival mediated by BphP by identifying the conditions under which DrBphP exhibits a fitness advantage.

Dataset Information

Knockout of pprM Decreases Resistance to Desiccation and Oxidation in Deinococcus radiodurans.

Publications

Knockout of <i>pprM</i> Decreases Resistance to Desiccation and Oxidation in <i>Deinococcus radiodurans</i>.

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