Chloramphenicol enhances Photosystem II photodamage in intact cells of the cyanobacterium Synechocystis PCC 6803
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ORIGINAL ARTICLE
Chloramphenicol enhances Photosystem II photodamage in intact cells of the cyanobacterium Synechocystis PCC 6803 Sandeesha Kodru1,2 · Ateeq ur Rehman1 · Imre Vass1 Received: 18 May 2020 / Accepted: 9 September 2020 / Published online: 26 September 2020 © The Author(s) 2020
Abstract The effect of chloramphenicol, an often used protein synthesis inhibitor, in photosynthetic systems was studied on the rate of Photosystem II (PSII) photodamage in the cyanobacterium Synechocystis PCC 6803. Light-induced loss of PSII activity was compared in the presence of chloramphenicol and another protein synthesis inhibitor, lincomycin, by measuring the rate of oxygen evolution in Synechocystis 6803 cells. Our data show that the rate of PSII photodamage was significantly enhanced by chloramphenicol, at the usually applied 200 μg m L−1 concentration, relative to that obtained in the presence of lincomycin. Chloramphenicol-induced enhancement of photodamage has been observed earlier in isolated PSII membrane particles, and has been assigned to the damaging effect of chloramphenicol-mediated superoxide production (Rehman et al. 2016, Front Plant Sci 7:479). This effect points to the involvement of superoxide as damaging agent in the presence of chloramphenicol also in Synechocystis cells. The chloramphenicol-induced enhancement of photodamage was observed not only in wild-type Synechocystis 6803, which contains both Photosystem I (PSI) and PSII, but also in a PSI-less mutant which contains only PSII. Importantly, the rate of PSII photodamage was also enhanced by the absence of PSI when compared to that in the wild-type strain under all conditions studied here, i.e., without addition and in the presence of protein synthesis inhibitors. We conclude that chloramphenicol enhances photodamage mostly by its interaction with PSII, leading probably to superoxide production. The presence of PSI is also an important regulatory factor of PSII photodamage most likely via decreasing excitation pressure on PSII. Keywords Chloramphenicol · Photoinhibition · Photosystem I · Photosystem II · Superoxide · Synechocystis PCC 6803 Abbreviations Chl Chlorophyll DMBQ 2,6-Dimethoxy-1,4-benzoquinone PSI Photosystem I PSII Photosystem II
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11120-020-00784-1) contains supplementary material, which is available to authorized users. * Imre Vass [email protected] 1
Institute of Plant Biology, Biological Research Centre, Temesvari krt. 62, Szeged 6726, Hungary
Doctoral School of Biology, University of Szeged, Szeged, Hungary
2
Introduction Photosynthesis is a process in which green plants, algae, and cyanobacteria utilize energy from sunlight to produce carbohydrates from carbon dioxide and water. This process is the ultimate source of energy for all plants to drive their metabolic processes. Too much light reaching the photosynthetic apparatus can cause photodamage and finally can lead to the death of a cell, a phenomenon called photoi
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