Excitation Energy Transfer and Charge Separation in Photosystem II Membranes Revisited

Broess, Koen; Trinkunas, Gediminas; Wit, Chantal D. van der Weij-de; Dekker, Jan; Hoek, A. van; Amerongen, Herbert van

doi:10.1529/biophysj.106.085068

Cited by 94 publications

(185 citation statements)

References 41 publications

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“…The 18 ps phase of the native membranes seems to lack a significant contribution of PSII. This is consistent with an organization of PSII in larger complexes than cores in these conditions, since PSII cores have a major trapping time of about 40 ps (Miloslavina et al 2006), whereas trapping in PSII membranes occurs on a longer time-scale (Broess et al 2006). The DAS of the unstacked membranes, extends to the blue with respect to the native DAS, with its maximum at 680 nm, but moreover it shows a small rise of fluorescence around 730 nm.…”

Section: Room Temperature Time-resolved Fluorescencesupporting

confidence: 85%

“…Also this phase is much stronger in unstacked membranes than in native membranes. Both PSI and PSII trap excitation energy by charge separation in their reaction centers at this timescale: PSI-LHCI has been shown to have a second main trapping phase of about 100 ps that is characterized by a redshifted spectrum , while the overall excitation decay of PSII in PSII membranes is around 150 ps (Van Mieghem et al 1992;Broess et al 2006). As the PSI antenna size has increased at the expense of the PSII antenna in unstacked membranes (see Fig.…”

Section: Room Temperature Time-resolved Fluorescencementioning

confidence: 98%

“…This phase is much stronger in the native membranes. It is known that PSI has trapped all absorbed energy within 120 ps , whereas the overall excitation decay of PSII in PSII membranes occurs on a timescale of 150 ps (Van Mieghem et al 1992;Broess et al 2006). Thus, we assign this long phase to the presence of a fraction of closed PSII reaction centers.…”

Section: Room Temperature Time-resolved Fluorescencementioning

confidence: 99%

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Excitation energy transfer in native and unstacked thylakoid membranes studied by low temperature and ultrafast fluorescence spectroscopy

et al. 2007

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In this work, the transfer of excitation energy was studied in native and cation-depletion induced, unstacked thylakoid membranes of spinach by steady-state and time-resolved fluorescence spectroscopy. Fluorescence emission spectra at 5 K show an increase in photosystem I (PSI) emission upon unstacking, which suggests an increase of its antenna size. Fluorescence excitation measurements at 77 K indicate that the increase of PSI emission upon unstacking is caused both by a direct spillover from the photosystem II (PSII) core antenna and by a functional association of light-harvesting complex II (LHCII) to PSI, which is most likely caused by the formation of LHCII-LHCI-PSI supercomplexes. Time-resolved fluorescence measurements, both at room temperature and at 77 K, reveal differences in the fluorescence decay kinetics of stacked and unstacked membranes. Energy transfer between LHCII and PSI is observed to take place within 25 ps at room temperature and within 38 ps at 77 K, consistent with the formation of LHCII-LHCI-PSI supercomplexes. At the 150-160 ps timescale, both energy transfer from LHCII to PSI as well as spillover from the core antenna of PSII to PSI is shown to occur at 77 K. At room temperature the spillover and energy transfer to PSI is less clear at the 150 ps timescale, because these processes compete with charge separation in the PSII reaction center, which also takes place at a timescale of about 150 ps.

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Section: Room Temperature Time-resolved Fluorescencesupporting

confidence: 85%

Section: Room Temperature Time-resolved Fluorescencementioning

confidence: 98%

Section: Room Temperature Time-resolved Fluorescencementioning

confidence: 99%

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Excitation energy transfer in native and unstacked thylakoid membranes studied by low temperature and ultrafast fluorescence spectroscopy

et al. 2007

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“…2G) in ΔPSI/II, and we observed no clear evidence of CFL 170 ps . Because CFL 170 ps is close to the values obtained for PSII membranes (16), the absence of CFL 170 ps was likely due to the lack of PSII in the mutant. We also observed no clear CFL shift in ΔPSI/II under the state 2-inducing conditions ( Fig.…”

Section: Chlorophyll Fluorescence Lifetime Of Dissociated Phospho-lhcsupporting

confidence: 69%

Live-cell imaging of photosystem II antenna dissociation during state transitions

Iwai

Yokono²,

Inada³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

122

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Plants and green algae maintain efficient photosynthesis under changing light environments by adjusting their light-harvesting capacity. It has been suggested that energy redistribution is brought about by shuttling the light-harvesting antenna complex II (LHCII) between photosystem II (PSII) and photosystem I (PSI) (state transitions), but such molecular remodeling has never been demonstrated in vivo. Here, using chlorophyll fluorescence lifetime imaging microscopy, we visualized phospho-LHCII dissociation from PSII in live cells of the green alga Chlamydomonas reinhardtii. Induction of energy redistribution in wild-type cells led to an increase in, and spreading of, a 250-ps lifetime chlorophyll fluorescence component, which was not observed in the stt7 mutant incapable of state transitions. The 250-ps component was also the dominant component in a mutant containing the light-harvesting antenna complexes but no photosystems. The appearance of the 250-ps component was accompanied by activation of LHCII phosphorylation, supporting the visualization of phospho-LHCII dissociation. Possible implications of the unbound phospho-LHCII on energy dissipation are discussed.photosynthesis | fluorescence lifetime imaging microscopy | green algae | light-harvesting | energy dissipation I n the thylakoid membranes of chloroplasts, photosystems I and II (PSI and PSII) work in concert to carry out photosynthetic electron transfer from water to NADP + . For efficient photosynthesis under changing light conditions, balancing absorbed light energy between the two photosystems, or state transition, is important (1-3). The plastoquinone (PQ) pool, an intersystem electron carrier, monitors changes in light quality and quantity and activates a protein kinase for light-harvesting complex (LHC) II (3-5). LHCII phosphorylation leads to a decrease in PSII light absorption (6, 7), which occurs on a timescale of minutes without any changes in gene expression. The decrease is therefore considered to be due to the reorganization of the PSII antenna system, such as dissociation of phospho-LHCII from PSII.The fate of dissociated phospho-LHCII has been investigated in vitro. Subfractionation of phosphorylated thylakoid membranes showed that the stroma lamella (non-appressed) fraction, where PSI was predominantly located, contained more phospho-LHCII than the grana (appressed) fraction, where PSII was predominantly located (8-10). Isolation of PSII under PQ pool-oxidizing conditions provided the evidence that unphospho-LHCII remained bound to PSII, whereas under PQ pool-reducing conditions phospho-LHCII was dissociated from PSII (11). Isolation of PSI under the same conditions revealed that the dissociated LHCII (including both major and minor LHCII) were reassociated with PSI (12). Thus, state transitions are accompanied by LHCII relocation between the two photosystems.However, because such LHCII migrations have been observed only in vitro, it still remains to be uncovered what happens during the LHCII migration in vivo. Does LHCII really disso...

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“…Moreover, the observed spectral alterations induced by quenching were completely reversible (15). LHCII is the major contributor to the room temperature fluorescence of intact chloroplasts due to the shallowness of the PSII reaction center trap, its excitation diffusion limited kinetics and the relative size of the peripheral antenna (ϳ250 chlorophylls) compared with the CP43/47 core antenna (ϳ36 chlorophylls) (33). Nonetheless, the enhancement of the vibronic satellite in isolated chloroplasts is likely to be due, at least in part, to an increased relative contribution from photosystem I (PSI) fluorescence particularly at ϳ720 nm, because of quenching of PSII fluorescence.…”

mentioning

confidence: 99%

Photoprotective Energy Dissipation in Higher Plants Involves Alteration of the Excited State Energy of the Emitting Chlorophyll(s) in the Light Harvesting Antenna II (LHCII)

Johnson

Ruban

2009

Journal of Biological Chemistry

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The photosynthetic apparatus of plants and algae has evolved a process of feedback control of energy input into the photosynthetic reaction centers, revealed in observations of the nonphotochemical quenching of chlorophyll fluorescence (NPQ) 2 (1-3). Exposure to high light intensity leads to closure of a large fraction of photosystem II (PSII) reaction centers and the buildup of the proton gradient across the photosynthetic membrane (⌬pH). The latter prompts the transition of the PSII light harvesting antenna (LHCII) into the photoprotective state (4 -6), where a large proportion of the absorbed energy is rapidly converted into heat, preventing photoinhibitory damage of reaction centers. The molecular mechanism of NPQ is currently under scrupulous multidisciplinary investigation (7-14).Many of these studies have centered on the search for pigments associated with light harvesting complexes that may act as energy traps/quenchers. In recent years certain evidence has accumulated that xanthophylls may play a central role in photoprotective energy dissipation. A carotenoid radical cation, suggested to be zeaxanthin, was found to correlate with the level of NPQ and was proposed to act as a direct quencher of chlorophyll excitation (7, 10). Other studies indicated the involvement of energy transfer to the S 1 state of LHCII-bound lutein 1 (9, 15). Evidence of these putative quenchers occurring in vivo was provided (7, 9), yet little is known about how ⌬pH activates them. ⌬pH is believed to protonate luminal residues on the PSII subunit PsbS and LHC complexes causing certain conformational changes to occur, which are necessary for NPQ (5, 6). These conformational changes are not well understood but can be traced by changes in LHCII-bound pigments detected by absorption and resonance Raman spectroscopy (9,(15)(16)(17)(18)(19)(20).Both the proposed zeaxanthin-and lutein-quenching mechanisms assume very close (van der Waals) contact between the quenching xanthophyll and chlorophyll. Such an interaction would, most likely, affect the energy levels of the pigments involved, which may be required to convert the xanthophyll into an energy quencher. Indeed, a subpopulation of zeaxanthin molecules in PSII was reported to undergo an absorption redshift in the NPQ state (18 -20). Recently, lutein absorption was also found to be decreased in the dissipative state (20), interestingly this loss of molar extinction was enhanced by the presence of zeaxanthin.Whereas many studies have probed the role of xanthophylls, relatively little is known about the state of chlorophylls upon formation of NPQ. Some research suggests that chlorophyll associates may be formed in the NPQ state, which potentially could act as quenchers (21-23). It has been proposed that such associates have red-shifted absorption and fluorescence spectra. Low temperature (77K) fluorescence spectra of quenched LHCII aggregates possess a 20-nm red-shifted band, F700 (22), which was also detected in leaves and thylakoids frozen in the NPQ state (21, 24). The F700 emitting...

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Excitation Energy Transfer and Charge Separation in Photosystem II Membranes Revisited

Cited by 94 publications

References 41 publications

Excitation energy transfer in native and unstacked thylakoid membranes studied by low temperature and ultrafast fluorescence spectroscopy

Excitation energy transfer in native and unstacked thylakoid membranes studied by low temperature and ultrafast fluorescence spectroscopy

Live-cell imaging of photosystem II antenna dissociation during state transitions

Photoprotective Energy Dissipation in Higher Plants Involves Alteration of the Excited State Energy of the Emitting Chlorophyll(s) in the Light Harvesting Antenna II (LHCII)

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