title: Expression of a highly active catalase VktA in the cyanobacterium Synechococcus elongatus PCC 7942 alleviates the photoinhibition of photosystem II.
abstract: The repair of photosystem II (PSII) after photodamage is particularly sensitive to reactive oxygen species-such as H2O2, which is abundantly produced during the photoinhibition of PSII. In the present study, we generated a transformant of the cyanobacterium Synechococcus elongatus PCC 7942 that expressed a highly active catalase, VktA, which is derived from a facultatively psychrophilic bacterium Vibrio rumoiensis, and examined the effect of expression of VktA on the photoinhibition of PSII. The activity of PSII in transformed cells declined much more slowly than in wild-type cells when cells were exposed to strong light in the presence of H2O2. However, the rate of photodamage to PSII, as monitored in the presence of chloramphenicol, was the same in the two lines of cells, suggesting that the repair of PSII was protected by the expression of VktA. The de novo synthesis of the D1 protein, which is required for the repair of PSII, was activated in transformed cells under the same stress conditions. Similar protection of the repair of PSII in transformed cells was also observed under strong light at a relatively low temperature. Thus, the expression of the highly active catalase mitigates photoinhibition of PSII by protecting protein synthesis against damage by H2O2 with subsequent enhancement of the repair of PSII.
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan.
authors: Haruhiko
authors: H
authors: Jimbo
authors: Akiko
authors: A
authors: Noda
authors: Hidenori
authors: H
authors: Hayashi
authors: Takanori
authors: T
authors: Nagano
authors: Isao
authors: I
authors: Yumoto
authors: Yoshitake
authors: Y
authors: Orikasa
authors: Hidetoshi
authors: H
authors: Okuyama
authors: Yoshitaka
authors: Y
authors: Nishiyama
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics; D006861:Hydrogen Peroxide / Q000494:pharmacology; D055668:Photochemical Processes / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D046940:Synechococcus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D014733:Vibrio / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D006861:Hydrogen Peroxide; D002374:Catalase