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PMID:11485197
| Citation |
Leisinger, U, Rüfenacht, K, Fischer, B, Pesaro, M, Spengler, A, Zehnder, AJ and Eggen, RI (2001) The glutathione peroxidase homologous gene from Chlamydomonas reinhardtii is transcriptionally up-regulated by singlet oxygen. Plant Mol. Biol. 46:395-408 |
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| 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. |
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| Keywords |
Algal Proteins/genetics; Animals; Arylsulfatases/drug effects; Arylsulfatases/genetics; Arylsulfatases/metabolism; Chlamydomonas reinhardtii/genetics; Dose-Response Relationship, Drug; Glutathione Peroxidase/genetics; HSP70 Heat-Shock Proteins/genetics; Hydrogen Peroxide/pharmacology; Light; Oxidative Stress; Oxygen/metabolism; Oxygen/pharmacology; Photosensitizing Agents/pharmacology; RNA, Messenger/drug effects; RNA, Messenger/metabolism; RNA, Messenger/radiation effects; Recombinant Fusion Proteins/drug effects; Recombinant Fusion Proteins/genetics; Recombinant Fusion Proteins/metabolism; Sequence Deletion; Singlet Oxygen; Superoxide Dismutase/genetics; Transcriptional Activation/drug effects; Transcriptional Activation/radiation effects; Up-Regulation/drug effects; Up-Regulation/radiation effects |
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Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0071452: cellular response to singlet oxygen |
ECO:0000314: |
P |
Figure 4 shows that when C. reinhardtii was shifted to light and the singlet oxygen photosensitizer neutral red was added to the culture there was a significant increase in the amount of gpxh mRNA. Whereas when the culture is in the dark there was minimal gpxh mRNA and when they were just exposed to light, the mRNA expression level was between the previous two conditions. |
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