Light capture by chlorophylls and photosynthetic electron transport bury the risk of the generation of reactive oxygen species (ROS) including singlet oxygen, superoxide anion radicals and hydrogen peroxide. Rapid changes in light intensity, electron fluxes and accumulation of strong oxidants and reductants increase ROS production. Superoxide is mainly generated at the level of photosystem I while photosystem II is the main source of singlet oxygen. ROS can induce oxidative damage of the photosynthetic apparatus, however, ROS are also important to tune processes inside the chloroplast and participate in retrograde signalling regulating the expression of genes involved in acclimation responses. Under most physiological conditions light harvesting and photosynthetic electron transport are regulated to keep the level of ROS at a non-destructive level. Photosystem II is most prone to photoinhibition but can be quickly repaired while photosystem I is protected in most cases. The size of the transmembrane proton gradient is central for the onset of mechanisms that protect against photoinhibition. The proton gradient allows dissipation of excess energy as heat in the antenna systems and it regulates electron transport. pH-dependent slowing down of electron donation to photosystem I protects it against ROS generation and damage. Cyclic electron transfer and photoreduction of oxygen contribute to the size of the proton gradient. The yield of singlet oxygen production in photosystem II is regulated by changes in the midpoint potential of its primary quinone acceptor. In addition, numerous antioxidants inside the photosystems, the antenna and the thylakoid membrane quench or scavenge ROS.
-
Cover Image
Cover Image
The flower represents the Drosophila testis niche with the hub cells at the center. Each petal of the flower represents Germline stem cells (GSCs) with a large and a smaller purple circle representing centromere; green rays representing stronger centromeres preferentially attach to the niche. Red and green caterpillars represent sister chromatids in prometaphase with separable old and new H3 in GSCs. Further, large butterflies closer to the flower represent prometaphase GSCs with a red wing vs a green wing representing non-overlapping old and new H3. Small orange butterflies away from the flower represent prophase gonialblast cells with overlapping old and new H3 signals. The background is from coiled sperm from the fly testis. Cover art generated by Professor Tim Phelps.
Regulation of the generation of reactive oxygen species during photosynthetic electron transport
Anja Krieger-Liszkay, Ginga Shimakawa; Regulation of the generation of reactive oxygen species during photosynthetic electron transport. Biochem Soc Trans 29 April 2022; 50 (2): 1025–1034. doi: https://doi.org/10.1042/BST20211246
Download citation file:
Sign in
Sign in to your personal account
Captcha Validation Error. Please try again.