Journal
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
Volume 1862, Issue 12, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.bbabio.2021.148494
Keywords
Nitrogen starvation; Phycobiliproteins; Photosystem II; Orange Carotenoid Protein
Categories
Funding
- Russian Science Foundation [21-44-00005]
- German Research Foundation DFG [FR 1276/5-1, FR1276/6-1]
- National Natural Science Foundation of China [42061134020]
- Program of the Russian Ministry of Science and Higher Education
- Russian Science Foundation [21-44-00005] Funding Source: Russian Science Foundation
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The quenching of excess excitation energy is crucial for photoprotection of light-harvesting complexes, especially in cyanobacteria where the Orange Carotenoid Protein (OCP) induces quenching of phycobilisome (PBS) excitation energy. OCP-dependent quenching affects approximately half of the PBSs coupled to PS II, suggesting that the concentration of OCP may not be sufficient for quenching all PBSs under normal conditions.
Quenching of excess excitation energy is necessary for the photoprotection of light-harvesting complexes. In cyanobacteria, quenching of phycobilisome (PBS) excitation energy is induced by the Orange Carotenoid Protein (OCP), which becomes photoactivated under high light conditions. A decrease in energy transfer efficiency from the PBSs to the reaction centers decreases photosystem II (PS II) activity. However, quantitative analysis of OCPinduced photoprotection in vivo is complicated by similar effects of both photochemical and non-photochemical quenching on the quantum yield of the PBS fluorescence overlapping with the emission of chlorophyll. In the present study, we have analyzed chlorophyll a fluorescence induction to estimate the effective cross-section of PS II and compared the effects of reversible OCP-dependent quenching of PBS fluorescence with reduction of PBS content upon nitrogen starvation or mutations of key PBS components. This approach allowed us to estimate the dependency of the rate constant of PS II primary electron acceptor reduction on the amount of PBSs in the cell. We found that OCP-dependent quenching triggered by blue light affects approximately half of PBSs coupled to PS II, indicating that under normal conditions, the concentration of OCP is not sufficient for quenching of all PBSs coupled to PS II.
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