The PSBP2 protein of Chlamydomonas reinhardtii is required for singlet oxygen-dependent signaling.
In the green alga Chlamydomonas reinhardtii, the cytosolic Glutathione Peroxidase 5 gene (GPX5) is known to be transcriptionally up-regulated in response to singlet oxygen ((1)O(2)). As demonstrated by previous studies, fusion of the promoter region of GPX5 to the Arylsulfatase 2 gene (ARS2) creates an effective reporter system that can be used to monitor (1)O(2)-driven GPX5 expression. This system was also used in this study to generate a stably transformed C. reinhardtii strain which expresses ARS2 in a (1)O(2)-dependent manner, resulting in the synthesis of a functional protein with detectable activity. Using the strain of C. reinhardtii harboring a (1)O(2)-sensitive reporter construct, a secondary mutagenic screen was performed. This allowed identification of mutant cell lines that were unable to up-regulate expression of the GPX5-ARS2 fusion in response to (1)O(2). In one of these lines, the mutation was subsequently localized to the first exon of the PSBP-like gene (PSBP2). The PSBP2 gene is part of a small protein family in C. reinhardtii, also present in all angiosperms studied thus far. While each member of the PSBP protein family contains a similar domain to the PSBP1 protein, which is a member of the oxygen evolving complex of photosystem II (PSII), the PSBP2 protein does not appear to be involved in PSII function, but may function as a sensor and/or signal mediating molecule of the (1)O(2) generated in the chloroplast.
Department of Biology, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.
Pawel
P
Brzezowski
Kenneth E
KE
Wilson
Gordon R
GR
Gray
D000222:Adaptation, Physiological; D001192:Arylsulfatases / Q000235:genetics / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D008027:Light; D009154:Mutation; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D010802:Phylogeny; D010940:Plant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D018749:RNA, Plant / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D026082:Singlet Oxygen / Q000494:pharmacology*; D015854:Up-Regulation
D010940:Plant Proteins; D018749:RNA, Plant; D002734:Chlorophyll; D026082:Singlet Oxygen; D005979:Glutathione Peroxidase; C080439:selenium-independent glutathione peroxidase; D001192:Arylsulfatases; D010100:Oxygen