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Probing the role of arginine 323 of the D1 protein in photosystem II function
Author(s) -
Sugiura Miwa,
Taniguchi Tomonori,
Tango Nanami,
Nakamura Makoto,
Sellés Julien,
Boussac Alain
Publication year - 2021
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.13115
Subject(s) - photosystem ii , dcmu , electron paramagnetic resonance , chemistry , protonation , kinetics , photosystem i , oxygen evolution , photochemistry , crystallography , stereochemistry , analytical chemistry (journal) , photosynthesis , biochemistry , nuclear magnetic resonance , ion , physics , organic chemistry , quantum mechanics , electrode , chromatography , electrochemistry
The Mn 4 CaO 5 cluster of photosystem II (PSII) advances sequentially through five oxidation states (S 0 to S 4 ). Under the enzyme cycle, two water molecules are oxidized, O 2 is generated and four protons are released into the lumen. Umena et al. (2011) have proposed that, with other charged amino acids, the R323 residue of the D1 protein could contribute to regulate a proton egress pathway from the Mn 4 CaO 5 cluster and Tyr Z via a proton channel identified from the 3D structure. To test this suggestion, a PsbA3/R323E site‐directed mutant has been constructed and the properties of its PSII have been compared to those of the PsbA3‐PSII by using EPR spectroscopy, polarography, thermoluminescence and time‐resolved UV–visible absorption spectroscopy. Neither the oscillations with a period four nor the kinetics and S‐state‐dependent stoichiometry of the proton release were affected. However, several differences have been found: (1) the P 680 + decay in the hundreds of ns time domain was much slower in the mutant, (2) the S 2 Q A − /DCMU and S 3 Q A − /DCMU radiative charge recombination occurred at higher temperatures and (3) the S 0 Tyr Z • , S 1 Tyr Z • , S 2 Tyr Z • split EPR signals induced at 4.2 K by visible light from the S 0 Tyr Z , S 1 Tyr Z , S 2 Tyr Z , respectively, and the (S 2 Tyr Z • )' induced by NIR illumination at 4.2 K of the S 3 Tyr Z state differed. It is proposed that the R323 residue of the D1 protein interacts with Tyr Z likely via the H‐bond network previously proposed to be a proton channel. Therefore, rather than participating in the egress of protons to the lumen, this channel could be involved in the relaxations of the H‐bonds around Tyr Z by interacting with the bulk, thus tuning the driving force required for Tyr Z oxidation.