Stabilization of Photosystem II by the PsbT protein impacts photodamage, repair and biogenesis

Fagerlund, Robert D.; Forsman, Jack; Biswas, Sandeep; Vass, Imre; Davies, Fiona K.; Summerfield, Tina C.; Eaton‐Rye, Julian J.

doi:10.1016/j.bbabio.2020.148234

Cited by 33 publications

(58 citation statements)

References 51 publications

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“…In contrast, measurements with isolated active PSII performed in the presence of the quinone analogue DCBQ (Fig. 3c, blue trace) had similar curve shapes to traces obtained with dark-adapted whole-cell measurements [19,31,33,37]. Most striking is the decreased O-J transition amplitude, dropping from 82.3 % to 59 % with the electron acceptor's addition (Table 1), indicating a robust forward electron transfer to DCBQ and a slower accumulation of QA -, more comparable to fluorescence induction traces measured in-vivo, demonstrating that this feature is extremely sensitive to the presence of electron acceptor molecules.…”

Section: Blocking Forward Electron Flow Increased the J-peak Intensity In The Ojip Fluorescence Transientsupporting

confidence: 57%

“…A similar J-peak increase after the addition of DCMU was observed with whole-cell Synechocystis sp. PCC 6803 variable chlorophyll fluorescence induction measurements [31,32]. This drastic increase in J-peak intensity indicates that blocked forward electron flow allows for a faster complete reduction of QA, the primary electron acceptor [33].…”

Section: Blocking Forward Electron Flow Increased the J-peak Intensity In The Ojip Fluorescence Transientmentioning

confidence: 98%

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OJIP chlorophyll fluorescence induction profiles and plastoquinone binding affinity of the Photosystem II assembly intermediate PSII-I from Thermosynechococcus elongatus

Zabret

Nowaczyk

2021

Preprint

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Binding of Psb28 to the photosystem II assembly intermediate PSII-I induces conformational changes to the PSII acceptor side that impact charge recombination and reduce the in situ production of singlet oxygen (Zabret et al. 2021, Nat. Plants 7, 524-538). A detailed fluorometric analysis of the PSII-I assembly intermediate compared with OEC-disrupted and Mn-depleted PSII complexes showed differences between their variable (OJIP) chlorophyll fluorescence induction profiles. These revealed a distinct destabilisation of the QA- state in the PSII-I assembly intermediate and inactivated PSII samples related to an increased rate of direct and safe charge recombination. Furthermore, inactivation or removal of the OEC increases the binding affinity for plastoquinone analogues like DCBQ to the different PSII complexes. These results might indicate a mechanism that further contributes to the protection of PSII during biogenesis or repair.

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Section: Blocking Forward Electron Flow Increased the J-peak Intensity In The Ojip Fluorescence Transientsupporting

confidence: 57%

Section: Blocking Forward Electron Flow Increased the J-peak Intensity In The Ojip Fluorescence Transientmentioning

confidence: 98%

OJIP chlorophyll fluorescence induction profiles and plastoquinone binding affinity of the Photosystem II assembly intermediate PSII-I from Thermosynechococcus elongatus

Zabret

Nowaczyk

2021

Preprint

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“…Stabilization of the Q B /Q B •− couple has been described previously in Synechocystis PCC 6803 mutants, mutated in the D‐de loop of the D2 protein, which showed an upshift of the B‐band (Kless et al, 2008; Mäenpää et al, 1995) and in the Synechocystis PCC 6803 ΔPsbT strain. Stabilization of S 2 Q B − has been correlated with increased light sensitivity (Fagerlund et al, 2020). Further studies are required to show whether mild drought stress protects higher plants against photoinhibition or increases the susceptibility to photoinhibition.…”

Section: Discussionmentioning

confidence: 99%

Moderate drought stress stabilizes the primary quinone acceptor Q_A and the secondary quinone acceptor Q_B in photosystem II

Leverne

Krieger‐Liszkay

2020

Physiologia Plantarum

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Drought induces stomata closure and lowers the CO2 concentration in the mesophyll, limiting CO2 assimilation and favoring photorespiration. The photosynthetic apparatus is protected under drought conditions by a number of downregulation mechanisms like photosynthetic control and activation of cyclic electron transport leading to the generation of a high proton gradient across the thylakoid membrane. Here, we studied photosynthetic electron transport by chlorophyll fluorescence, thermoluminescence (TL), and P700 absorption measurements in spinach exposed to moderate drought stress. Chlorophyll fluorescence induction and decay kinetics were slowed down. Under drought conditions, an increase of the TL AG‐band and a downshift of the maximum temperatures of both, the B‐band and the AG‐band, were observed when leaves were illuminated under conditions that maintained the proton gradient. When leaves were frozen prior to the TL measurements, the maximum temperature of the B‐band was upshifted in drought‐stressed leaves. This shows a stabilization of the QB/QB•− redox couple in accordance with the slower fluorescence decay kinetics. We propose that during drought stress, photorespiration exerts a feedback control on photosystem II via the binding of a photorespiratory metabolite at the non‐heme iron at the acceptor side of photosystem II. According to our hypothesis, an exchange of bicarbonate at the non‐heme iron by a photorespiratory metabolite such as glycolate would not only affect the midpoint potential of the QA/QA•− couple, as shown previously, but also that of the QB/QB•− couple.

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“…Variable chlorophyll a fluorescence measurements were made with the same fluorometer using the protocol described in Fagerlund et al [21]. When present, 3,4dichloro-1,1-dimethyl urea (DCMU) was added at 40 µM.…”

Section: Oxygen Evolution Assaysmentioning

confidence: 99%

The D1:Ser268 residue of Photosystem II contributes to an alternative pathway for Q_B protonation in the absence of bound bicarbonate

Forsman

Eaton‐Rye

2020

FEBS Letters

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Photosystem II catalyses the splitting of water and the reduction in plastoquinone in thylakoid membranes of all oxygenic photosynthetic organisms. The final step in quinol formation is protonation of the reduced secondary quinone electron acceptor normalQnormalB2‐false(H+false)to give QBH2. The proton for this step is hypothesized to be provided by a hydrogen‐bond network incorporating amino acids from the Photosystem II D1 and D2 reaction center proteins, together with several bound waters and a bicarbonate ion ligated to a non‐heme iron found between the primary plastoquinone electron acceptor QA and QB. The aim of this study was to investigate the role of bicarbonate and the D1:Ser268 residue in the formation of QBH2. Using targeted mutagenesis of the D1 protein in the cyanobacterium Synechocystis sp. PCC 6803, we have created two mutants, S268A and S268T. Our D1:Ser268 mutants exhibited increased sensitivity to formate‐induced inhibition of electron transfer between QA and QB and indicate that D1:Ser268 and bicarbonate support the second protonation in the formation of QBH2 via two different pathways that both lead to the protonation of normalQnormalB2‐false(H+false) by D1:His215.

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Stabilization of Photosystem II by the PsbT protein impacts photodamage, repair and biogenesis

Cited by 33 publications

References 51 publications

OJIP chlorophyll fluorescence induction profiles and plastoquinone binding affinity of the Photosystem II assembly intermediate PSII-I from Thermosynechococcus elongatus

OJIP chlorophyll fluorescence induction profiles and plastoquinone binding affinity of the Photosystem II assembly intermediate PSII-I from Thermosynechococcus elongatus

Moderate drought stress stabilizes the primary quinone acceptor Q_A and the secondary quinone acceptor Q_B in photosystem II

The D1:Ser268 residue of Photosystem II contributes to an alternative pathway for Q_B protonation in the absence of bound bicarbonate

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Stabilization of Photosystem II by the PsbT protein impacts photodamage, repair and biogenesis

Cited by 33 publications

References 51 publications

OJIP chlorophyll fluorescence induction profiles and plastoquinone binding affinity of the Photosystem II assembly intermediate PSII-I from Thermosynechococcus elongatus

OJIP chlorophyll fluorescence induction profiles and plastoquinone binding affinity of the Photosystem II assembly intermediate PSII-I from Thermosynechococcus elongatus

Moderate drought stress stabilizes the primary quinone acceptor QA and the secondary quinone acceptor QB in photosystem II

The D1:Ser268 residue of Photosystem II contributes to an alternative pathway for QB protonation in the absence of bound bicarbonate

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Moderate drought stress stabilizes the primary quinone acceptor Q_A and the secondary quinone acceptor Q_B in photosystem II

The D1:Ser268 residue of Photosystem II contributes to an alternative pathway for Q_B protonation in the absence of bound bicarbonate