Quality Control of Photosystem II: Lipid Peroxidation Accelerates Photoinhibition under Excessive Illumination

Abstract

Environmental stresses lower the efficiency of photosynthesis and sometimes cause irreversible damage to plant functions. When spinach thylakoids and Photosystem II membranes were illuminated with excessive visible light (100–1,000 µmol photons m−1 s−1) for 10 min at either 20°C or 30°C, the optimum quantum yield of Photosystem II decreased as the light intensity and temperature increased. Reactive oxygen species and endogenous cationic radicals produced through a photochemical reaction at and/or near the reaction center have been implicated in the damage to the D1 protein. Here we present evidence that lipid peroxidation induced by the illumination is involved in the damage to the D1 protein and the subunits of the light-harvesting complex of Photosystem II. This is reasoned from the results that considerable lipid peroxidation occurred in the thylakoids in the light, and that lipoxygenase externally added in the dark induced inhibition of Photosystem II activity in the thylakoids, production of singlet oxygen, which was monitored by electron paramagnetic resonance spin trapping, and damage to the D1 protein, in parallel with lipid peroxidation. Modification of the subunits of the light-harvesting complex of Photosystem II by malondialdehyde as well as oxidation of the subunits was also observed. We suggest that mainly singlet oxygen formed through lipid peroxidation under light stress participates in damaging the Photosystem II subunits.

Long-Chain Saturated Fatty Acids, Palmitic and Stearic Acids, Enhance the Repair of Photosystem II

“…Uncoupling ΔpH across the thylakoid membrane by the addition of NH 4 Cl or nigericin extends photodamage to PSII [ 21 , 22 ], which implies that incorporation of 18:3 into membrane lipids inhibits the formation of thylakoid ΔpH as well, which extends photodamage of PSII. In addition, PUFA easily become targets of ROS and the peroxidation of PUFA induces the photoinhibition of PSII [ 23 , 24 ]. A lack of α-tocopherol, a scavenger of singlet oxygen, increases lipid peroxidation and inhibits PSII repair under strong light [ 25 , 26 ].…”

Quality control of Photosystem II: reversible and irreversible protein aggregation decides the fate of Photosystem II under excessive illumination

“…At this stage, photoinhibition prevails over protection and repair, and PSII is in a typical photodamaging state where degradation of the damaged D1 protein takes place (Barber and Andersson, 1992; Aro et al, 1993). Irreversible aggregation or cross-linking of the photodamaged reaction center-binding D1 protein also occurs (Mori and Yamamoto, 1992; Mori et al, 1995; Yamamoto and Akasaka, 1995; Ishikawa et al, 1999; Yamamoto, 2001; Yamamoto et al, 2008; Khatoon et al, 2009; Chan et al, 2012). The irreversible aggregation of the D1 protein is ascribed to the covalent cross-linking of the protein with nearby polypeptides after photooxidative damage to the D1 protein under light stress.…”

Involvement of molecular oxygen in the donor-side photoinhibition of Mn-depleted photosystem II membranes

“…In this case, photoformation of ROO Á /ROOH may lead to changes on the donor side of PSII resulting in the loss of capability of PSII RCs to the redox interaction with exogenous electron donor, and the modifications can be an initial event to trigger the D1 protein degradation. Formation of lipid peroxides under photoinhibitory conditions in PSII membranes has been also shown recently (Chan et al 2012).…”