Chloramphenicol enhances Photosystem II photodamage in intact cells of the cyanobacterium Synechocystis PCC 6803

Sandeesha Kodru,Ateeq Ur Rehman,Imre Vass

doi:10.1007/s11120-020-00784-1

Sandeesha Kodru, Ateeq Ur Rehman + Show 1 more

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https://doi.org/10.1007/s11120-020-00784-1

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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 mL−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.

Highlights

Photosynthesis is a process in which green plants, algae, and cyanobacteria utilize energy from sunlight to produce carbohydrates from carbon dioxide and water
We have extended our earlier studies from isolated thylakoid membrane preparations to intact cell cultures of the cyanobacterium Synechocystis PCC 6803, as well as to its Photosystem I (PSI)-less mutant
In order to quantify the effect of 200 μg mL−1 chloramphenicol on the rate of Photosystem II (PSII) photodamage, WT Synechocystis cells were exposed to 500 μmol photons m −2 s−1 illumination without addition, and in the presence of either lincomycin or chloramphenicol as protein synthesis inhibitor

Summary

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 can lead to the death of a cell, a phenomenon called photoinhibition (Arntzen et al 1984; Aro et al 1993; Vass and Aro 2008; Zavafer et al 2017). The activity of the photodamaged PSII complex can be restored via the so-called PSII repair cycle, in which de novo synthesis of the D1 subunits plays a key role (Aro et al 1993; BaenaGonzalez and Aro 2002; Komenda et al 2007; Nixon et al 2010; Vass 2012; Järvi et al 2015; Li et al 2018)

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