Photoprotection through ultrafast charge recombination in photochemical reaction centres under oxidizing conditions

Ma, Fei, Swainsbury, David J. K., Jones, Michael R. and van Grondelle, Rienk (2017) Photoprotection through ultrafast charge recombination in photochemical reaction centres under oxidizing conditions. Philosophical Transactions of the Royal Society B: Biological Sciences, 372 (1730). ISSN 0962-8436

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Engineering natural photosynthesis to address predicted shortfalls in food and energy supply requires a detailed understanding of its molecular basis and the intrinsic photoprotective mechanisms that operate under fluctuating environmental conditions. Long-lived triplet or singlet excited electronic states have the potential to cause photodamage, particularly in the presence of oxygen, and so a variety of mechanisms exist to prevent formation of such states or safely dissipate their energy. Here, we report a dramatic difference in spectral evolution in fully reduced and partially oxidized Rhodobacter sphaeroides reaction centres (RCs) following excitation of the monomeric bacteriochlorophyll (BChl) cofactors at 805 nm. Three types of preparation were studied, including RCs purified as protein/lipid nano-discs using the copolymer styrene maleic acid. In fully reduced RCs such excitation produces membrane-spanning charge separation. In preparations of partially oxidized RCs the spectroscopic signature of this charge separation is replaced by that of an energy dissipation process, including in the majority sub-population of reduced RCs. This process, which appears to take place on both cofactor branches, involves formation of a BChl+/bacteriopheophytin- radical pair that dissipates energy via recombination to a vibrationally hot ground state. The possible physiological role of this dissipative process under mildly oxidizing conditions is considered. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.

Item Type: Article
Additional Information: Funding Information: F.M. and R.v.G. were supported by an Advanced Investigator grant from the European Research Council (grant no. 267333, PHOT-PROT) to R.v.G., the TOP-grant no (700.58.305) from the Foundation of Chemical Sciences part of NWO and the EU FP7 project PAPETS (GA 323901). R.v.G. gratefully acknowledges his Academy Professor grant from The Netherlands Royal Academy of Sciences. D.J.K.S. and M.R.J. were supported by the Biotechnology and Biological Sciences Research Council of the United Kingdom (project BB/I022570/1).
Uncontrolled Keywords: charge recombination,photoprotection,reaction centre,styrene maleic acid,ultrafast spectroscopy,biochemistry, genetics and molecular biology(all),agricultural and biological sciences(all) ,/dk/atira/pure/subjectarea/asjc/1300
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 17 Aug 2022 12:31
Last Modified: 22 Oct 2022 07:55
DOI: 10.1098/rstb.2016.0378

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