title: The glutathione peroxidase homologous gene from Chlamydomonas reinhardtii is transcriptionally up-regulated by singlet oxygen.
abstract: The glutathione peroxidase homologous gene (Gpxh gene) in Chlamydomonas reinhardtii is up-regulated under oxidative stress conditions. The Gpxh gene showed a remarkably strong and fast induction by the singlet oxygen-generating photosensitizers neutral red, methylene blue and rose Bengal. The Gpxh mRNA levels strongly increased, albeit much more slowly, upon exposure to the organic hydroperoxides tert-butyl hydroperoxide (t-BOOH) and cumene hydroperoxide. In contrast, the Gpxh mRNA levels were only weakly induced by exposure to the superoxide-generating compound paraquat and by hydrogen peroxide. A comparison of the Gpxh mRNA levels with those of the heat shock protein HSP70A and the iron superoxide dismutase gene showed qualitative and quantitative differences for the three genes under oxidative stress conditions tested. The Gpxh gene is specifically induced by singlet-oxygen photosensitizers and the relative induction by other compounds is much weaker for Gpxh than for the other genes investigated. Using Gpxh promoter fusions with the arylsulfatase reporter gene, we have shown that the Gpxh was transcriptionally up-regulated by singlet-oxygen photosensitizers. It is also shown that the Gpxh promoter contains a region between 104 and 179 bp upstream of the transcription start that is responsible for the mRNA up-regulation upon exposure to 1O2 but not t-BOOH. Within this region a regulatory sequence homologous to the mammalian cAMP response element (CRE) and activator protein 1 (AP-1) binding site was identified within a 16 bp palindrome.
authors.affiliation: Department of Environmental Microbiology and Molecular Ecotoxicology, Swiss Federal Institute for Environmental Science and Technology (EAWAG), Duebendorf.
authors.forename: U
authors.initials: U
authors.lastname: Leisinger
authors.forename: K
authors.initials: K
authors.lastname: Rüfenacht
authors.forename: B
authors.initials: B
authors.lastname: Fischer
authors.forename: M
authors.initials: M
authors.lastname: Pesaro
authors.forename: A
authors.initials: A
authors.lastname: Spengler
authors.forename: A J
authors.initials: AJ
authors.lastname: Zehnder
authors.forename: R I
authors.initials: RI
authors.lastname: Eggen
mesh_terms: D020418:Algal Proteins / Q000235:genetics*; D000818:Animals; D001192:Arylsulfatases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D005979:Glutathione Peroxidase / Q000235:genetics*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008027:Light; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism / Q000494:pharmacology*; D017319:Photosensitizing Agents / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D026082:Singlet Oxygen; D013482:Superoxide Dismutase / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects / Q000528:radiation effects; D015854:Up-Regulation / Q000187:drug effects / Q000528:radiation effects
chemical_list: D020418:Algal Proteins; D018840:HSP70 Heat-Shock Proteins; D017319:Photosensitizing Agents; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D026082:Singlet Oxygen; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D001192:Arylsulfatases; D010100:Oxygen