Oxidative stress response of Deinococcus geothermalis via a cystine importer

• Published in: The journal of microbiology 2017, 55(2), , pp.137-146
• Main Authors: Kim, Minwook, Jeong, Sunwook, Lim, Sangyong, Sim, Jeonggu, Rhie, Ho-Gun, Lee, Sung-Jae
• Format: Article
• Language: English
• Subjects: ABC transporters; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biomedical and Life Sciences; Catalase - genetics; Catalase - metabolism; Cysteine - metabolism; Cystine - metabolism; Deinococcus - drug effects; Deinococcus - genetics; Deinococcus - metabolism; Deinococcus geothermalis; DNA Damage; E coli; Enzymes; Genes; Genes, Bacterial; Gram-negative bacteria; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Hydrogen Peroxide - pharmacology; Life Sciences; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Microbial Physiology and Biochemistry; Microbiology; Multigene Family; Mutants; Mutation; Oxidation-Reduction; Oxidative stress; Oxidative Stress - genetics; Proteins; Radiation; Sulfhydryl Compounds - metabolism; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Survival; Yeast; 생물학
• ISSN: 1225-8873; 1976-3794
• DOI: 10.1007/s12275-017-6382-y

A cystine-dependent anti-oxidative stress response is characterized in Deinococcus geothermalis for the first time. Nevertheless, the same transcriptional directed Δdgeo_1985F mutant strain was revealed to have an identical phenotype to the wild-type strain, while the reverse transcriptional directed Δdgeo_1985R mutant strain was more resistant to oxidative stress at a certain concentration of H 2 O 2 than the wild-type strain. The wild-type and mutant strains expressed equal levels of superoxide dismutase and catalase under H 2 O 2 -induced stress. Although the expression levels of the general DNA-damage response-related genes recA , pprA , ddrA , and ddrB were up-regulated by more than five-fold in the wild-type strain relative to the Δdgeo_1985R mutant strain, the mutant strain had a higher survival rate than the wild-type under H 2 O 2 stress. The Δdgeo_1985R mutant strain highly expressed a cystine-transporter gene ( dgeo _1986), at levels 150-fold higher than the wild-type strain, leading to the conclusion that this cystine transporter might be involved in the defensive response to H 2 O 2 stress. In this study, the cystine transporter was identified and characterized through membrane protein expression analysis, a cystine-binding assay, and assays of intracellular H 2 O 2 , cysteine, and thiol levels. The genedisrupted mutant strain of the cystine importer revealed high sensitivity to H 2 O 2 and less absorbed cystine, resulting in low concentrations of total thiol. Thus, the absorbed cystine via this cystine-specific importer may be converted into cysteine, which acts as a primitive defense substrate that non-enzymatically scavenges oxidative stress agents in D. geothermalis .