Absorption changes in Photosystem II in the Soret band region upon the formation of the chlorophyll cation radical [PD1PD2]+

Abstract

individual Chl on the D1 or D2 side, respectively, which constitute a pair of Chl with partially overlapping aromatic rings (P680); PheD1 and PheD2, pheophytin on the D1 or D2 side, respectively; PPBQ, phenyl p-benzoquinone; PSII, Photosystem II; QA, primary quinone acceptor; QB, secondary quinone acceptor; Tyr D , the tyrosine 160 of D2 acting as a side-path electron donor of PSII; Tyr Z , the tyrosine 161 of D1 acting as the electron donor to P 680 ; WT*3, T. elongatus mutant strain deleted psbA1 and psbA2 genes and with a His-tag on the carboxy terminus of CP43; WT', T. elongatus mutant strain deleted psbA1, psbA2 and psbD2 genes and with a His-tag on the carboxy terminus of CP43. EDTA, Ethylenediaminetetraacetic acid.

Contributions of PD1 and PD2 to the [PD1PD2]+-minus-[PD1PD2] difference spectrum in the Soret region in Photosystem II

“…This comparison clearly shows that the main trough of the spectrum in wild-type Synechocystis 6803 is slightly blue-shifted when compared to the spectrum in T. elongatus (in contrast to the trough at 446 nm that is not affected). As we did not used the proper control spectrum in (Boussac et al 2023) (Rigby et al 1994, Diner et al 2001, Okubo et al 2007, Nagao et al 2017). Alternatively, it could be due to something more complex due to couplings between several pigments or charge fluctuations between them (Narzi et.…”

“…The additional feature was "W-shaped" with troughs at 434 nm and 446 nm. This double trough feature in the [P D1 P D2 ] + -minus-[P D1 P D2 ] difference spectrum was seemingly unmodified in all of the mutants studied except in the P D2 (Boussac et al 2023). Therefore, we have also measured this spectrum in Mn-depleted PsbA3/H198Q-PSII at pH 8.6, as for the other spectra, for a better comparison although the Mn-depletion seemed to have no detectable effect on these spectra.…”

“…We have therefore measured this difference spectrum in the present work. The [P D1 P D2 ] + - minus -[P D1 P D2 ] difference spectrum in the PsbA3/H198Q mutant was only reported in our previous work in O 2 -evolving PSII at low pH values (Boussac et al 2023). Therefore, we have also measured this spectrum in Mn-depleted PsbA3/H198Q-PSII at pH 8.6, as for the other spectra, for a better comparison although the Mn-depletion seemed to have no detectable effect on these spectra.…”

“…The His-tagged PSII samples from T. elongatus used in this study, PsbA1-PSII, PsbA3-PSII and PsbA3/H198Q-PSII, were purified as described previously (Boussac et al 2023). The His-tagged PSII samples from Synechocystis sp PCC 6803 used in this study, D2/H197A-PSII and WT-PSII (Hayase et al 2023), were purified as described previously (Boussac et al 2023). The Mn-depletion procedure has also been described previously (Boussac et al 2023).…”

“…The His-tagged PSII samples from Synechocystis sp PCC 6803 used in this study, D2/H197A-PSII and WT-PSII (Hayase et al 2023), were purified as described previously (Boussac et al 2023). The Mn-depletion procedure has also been described previously (Boussac et al 2023). In the last step, all the PSII samples were suspended in 1 M betaine, 15 mM CaCl 2 , 15 mM MgCl 2 , 100 mM Tris, pH 8.6.…”