<i>In vitro</i>
            reconstitution of the activated zeaxanthin state associated with energy dissipation in plants

Aspinall-O’Dea, Mark; Wentworth, Mark; Pascal, Andrew A.; Robert, Bruno; Ruban, Alexander V.; Horton, Peter

doi:10.1073/pnas.252500999

Cited by 116 publications

(115 citation statements)

References 32 publications

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“…The analysis of npq4, npq1 npq4, and npq2 npq4 mutants clearly shows that the modulation of NPQ rate by Zea fully depends on the presence of PsbS and therefore suggests that the site sensitive to the presence of zeaxanthin might be located in this gene product. Evidences for binding of pigments to PsbS is controversial (Funk et al, 1995;Aspinall-O'Dea et al, 2002;Dominici et al, 2002) but has been proposed to be a step in the mechanism of qE. The increased NPQ rate in npq2, but not in npq2 npq4, is consistent with the proposal that Zea binds to PsbS.…”

Section: Relation Between Ph-independent and Qe Quenching Typessupporting

confidence: 69%

A Mechanism of Nonphotochemical Energy Dissipation, Independent from PsbS, Revealed by a Conformational Change in the Antenna Protein CP26

2005

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The regulation of light harvesting in higher plant photosynthesis, defined as stress-dependent modulation of the ratio of energy transfer to the reaction centers versus heat dissipation, was studied by means of carotenoid biosynthesis mutants and recombinant light harvesting complexes (LHCs) with modified chromophore binding. The npq2 mutant of Arabidopsis thaliana, blocked in the biosynthesis of violaxanthin and thus accumulating zeaxanthin, was shown to have a lower fluorescence yield of chlorophyll in vivo and, correspondingly, a higher level of energy dissipation, with respect to the wildtype strain and npq1 mutant, the latter of which is incapable of zeaxanthin accumulation. Experiments on purified thylakoid membranes from all three mutants showed that the major source of the difference between the npq2 and wild-type preparations was a change in pigment to protein interactions, which can explain the lower chlorophyll fluorescence yield in the npq2 samples. Analysis of the xanthophyll binding LHC proteins showed that the Lhcb5 photosystem II subunit (also called CP26) undergoes a change in its pI upon binding of zeaxanthin. The same effect was observed in wild-type CP26 upon treatment that leads to the accumulation of zeaxanthin in the membrane and was interpreted as the consequence of a conformational change. This hypothesis was confirmed by the analysis of two recombinant proteins obtained by overexpression of the Lhcb5 apoprotein in Escherichia coli and reconstitution in vitro with either violaxanthin or zeaxanthin. The V and Z containing pigment-protein complexes obtained by this procedure showed different pIs and high and low fluorescence yields, respectively. These results confirm that LHC proteins exist in multiple conformations, an idea suggested by previous spectroscopic measurements ( Moya et al., 2001), and imply that the switch between the different LHC protein conformations is activated by the binding of zeaxanthin to the allosteric site L2. The results suggest that the quenching process induced by the accumulation of zeaxanthin contributes to qI, a component of NPQ whose origin was previously poorly understood.

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Section: Relation Between Ph-independent and Qe Quenching Typessupporting

confidence: 69%

A Mechanism of Nonphotochemical Energy Dissipation, Independent from PsbS, Revealed by a Conformational Change in the Antenna Protein CP26

2005

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“…PsbS is an Lhc-type protein (27), the role of which in the generation of qE is not fully understood. It is able to bind N,NЈ-dicyclohexylcarbodiimide (28), a qE inhibitor (11), and likely able to associate with carotenoids (29). PsbS can associate with either the antenna or the PSII core complex, thanks to a pH-dependent shift between a monomeric and a homodimeric form (30).…”

Section: Figmentioning

confidence: 99%

A zeaxanthin-independent nonphotochemical quenching mechanism localized in the photosystem II core complex

Finazzi

Johnson

Dall’Osto

et al. 2004

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

132

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Illumination of dark-adapted barley plants with low light transiently induced a large nonphotochemical quenching of chlorophyll fluorescence. This reaction was identified as a form of high-energy-state quenching. Its appearance was not accompanied by zeaxanthin synthesis but was associated with a reversible inactivation of a fraction of photosystem II (PSII) centers. Both the fluorescence quenching and PSII inactivation relaxed in parallel with the activation of the Calvin cycle. We interpret the induction of this phenomenon as due to the generation of a quenched state in the PSII core complex. This reaction is probably caused by the transient overacidification of the thylakoid lumen, whereas its dissipation results from the relaxation of both the pH gradient across the thylakoid membrane and redox pressure upon activation of carbon fixation. At saturating light intensities, inactivation of PSII was still observed at the onset of illumination, although its recovery did not result in dissipation of high-energy quenching, which presents typical characteristics of an antenna-associated quenching at steady state. Reaction-center quenching seems therefore to be a common transient feature during illumination, being replaced by other phenomena (photochemical or antenna quenching and photoinhibition), depending on the balance between light and carbon fixation fluxes

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“…PsbS is considered a member of the light-harvesting complex (LHC) superfamily, although it is predicted to have four rather than three transmembrane helices (3). Studies with native PsbS and PsbS refolded in vitro have been inconsistent with respect to its pigment-binding ability (4)(5)(6)(7)(8)(9)(10). One interesting feature of PsbS is its reported pH-dependent dimer-to-monomer transition under high-light conditions, thought to be due to the protonation of luminal glutamates (11,12).…”

mentioning

confidence: 99%

“…Whereas most previous in vitro studies were conducted with LHC-II (e.g., refs. 14, [23][24][25][26] or PsbS (7)(8)(9) in detergent solution, we present here a proteoliposome system that combines LHC-II, Zea, and PsbS to study Chl fluorescence quenching directly in the membrane.…”

mentioning

confidence: 99%

Direct interaction of the major light-harvesting complex II and PsbS in nonphotochemical quenching

Wilk

Grunwald

Liao

et al. 2013

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

101

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The photosystem II (PSII) subunit S (PsbS) plays a key role in nonphotochemical quenching, a photoprotective mechanism for dissipation of excess excitation energy in plants. The precise function of PsbS in nonphotochemical quenching is unknown. By reconstituting PsbS together with the major light-harvesting complex of PSII (LHC-II) and the xanthophyll zeaxanthin (Zea) into proteoliposomes, we have tested the individual contributions of PSII complexes and Zea to chlorophyll (Chl) fluorescence quenching in a membrane environment. We demonstrate that PsbS is stable in the absence of pigments in vitro. Significant Chl fluorescence quenching of reconstituted LHC-II was observed in the presence of PsbS and Zea, although neither Zea nor PsbS alone was sufficient to induce the same quenching. Coreconstitution with PsbS resulted in the formation of LHC-II/PsbS heterodimers, indicating their direct interaction in the lipid bilayer. Two-photon excitation measurements on liposomes containing LHC-II, PsbS, and Zea showed an increase of electronic interactions between carotenoid S 1 and Chl states, Φ CarS1−ChlCoupling , that correlated directly with Chl fluorescence quenching. These findings are in agreement with a carotenoid-dependent Chl fluorescence quenching by direct interactions of LHCs of PSII with PsbS monomers.

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In vitro reconstitution of the activated zeaxanthin state associated with energy dissipation in plants

Cited by 116 publications

References 32 publications

A Mechanism of Nonphotochemical Energy Dissipation, Independent from PsbS, Revealed by a Conformational Change in the Antenna Protein CP26

A Mechanism of Nonphotochemical Energy Dissipation, Independent from PsbS, Revealed by a Conformational Change in the Antenna Protein CP26

A zeaxanthin-independent nonphotochemical quenching mechanism localized in the photosystem II core complex

Direct interaction of the major light-harvesting complex II and PsbS in nonphotochemical quenching

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