Toward an Understanding of the Mechanism of Nonphotochemical Quenching in Green Plants

Holt, Nancy E.; Fleming, Graham R.; Niyogi, Krishna

doi:10.1021/bi0494020

Cited by 300 publications

(287 citation statements)

References 70 publications

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“…The control of the rate of the transition into and out of this state by the DES is consistent with the proposed role of the xanthophyll cycle carotenoids as allosteric regulators of qE [9,10]. The data could also be accommodated within a model in which the only role of zeaxanthin is as the direct quencher [8], either bound to PsbS [21], LHCII [22] or to a minor antenna complex [23,24]. However, important new features would need to be invoked: there must be competition between violaxanthin and zeaxanthin for the quenching site; and the rate of binding and release from this site must be rate limiting for qE formation and relaxation respectively.…”

Section: Discussionsupporting

confidence: 75%

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The xanthophyll cycle pool size controls the kinetics of non‐photochemical quenching in Arabidopsis thaliana

et al. 2007

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Arabidopsis plants overexpressing b-carotene hydroxylase 1 accumulate over double the amount of zeaxanthin present in wild-type plants. The final amplitude of non-photochemical quenching (NPQ) was found to be the same in these plants, but the kinetics were different. The formation and relaxation of NPQ consistently correlated with the de-epoxidation state of the xanthophyll cycle pool and not the amount of zeaxanthin. These data indicate that zeaxanthin and violaxanthin antagonistically regulate the switch between the light harvesting and photoprotective modes of the light harvesting system and show that control of the xanthophyll cycle pool size is necessary to optimize the kinetics of NPQ.

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Section: Discussionsupporting

confidence: 75%

“…There are two theories to explain the mechanism of action of these carotenoids in qE. Firstly, it has been proposed that zeaxanthin, but not violaxanthin, is a direct quencher of chlorophyll excited states [8]. Secondly, these carotenoids were suggested to allosterically regulate a quenching process that is intrinsic to LHCII [9,10].…”

Section: Introductionmentioning

confidence: 99%

The xanthophyll cycle pool size controls the kinetics of non‐photochemical quenching in Arabidopsis thaliana

et al. 2007

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“…The short lifetime component conformation is correlated with the dissipative state (Gilmore et al, 1998). Interconversion of the protein conformation between these two states would regulate the efficiency of energy transfer to the PSI I reaction centers (Holt et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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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“…Carotenoids, mainly xanthophylls, are the most prevalent yellow pigments found in flowers. Carotenoids are also synthesized in chloroplasts, where they play essential roles in photosynthesis in the light-harvesting systems and in the photosynthetic reaction centers (Frank et al, 1999;Demmig-Adams and Adams, 2002;Holt et al, 2004;Robert et al, 2004;Horton and Ruban, 2005;Standfuss et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

A Chromoplast-Specific Carotenoid Biosynthesis Pathway Is Revealed by Cloning of the Tomato white-flower Locus

et al. 2006

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Carotenoids and their oxygenated derivatives xanthophylls play essential roles in the pigmentation of flowers and fruits. Wild-type tomato (Solanum lycopersicum) flowers are intensely yellow due to accumulation of the xanthophylls neoxanthin and violaxanthin. To study the regulation of xanthophyll biosynthesis, we analyzed the mutant white-flower (wf). It was found that the recessive wf phenotype is caused by mutations in a flower-specific b-ring carotene hyroxylase gene (CrtR-b2). Two deletions and one exon-skipping mutation in different CrtR-b2 wf alleles abolish carotenoid biosynthesis in flowers but not leaves, where the homologous CrtR-b1 is constitutively expressed. A second b-carotene hydroxylase enzyme as well as flower-and fruit-specific geranylgeranyl diphosphate synthase, phytoene synthase, and lycopene b-cyclase together define a carotenoid biosynthesis pathway active in chromoplasts only, underscoring the crucial role of gene duplication in specialized plant metabolic pathways. We hypothesize that this pathway in tomato was initially selected during evolution to enhance flower coloration and only later recruited to enhance fruit pigmentation. The elimination of b-carotene hydroxylation in wf petals results in an 80% reduction in total carotenoid concentration, possibly caused by the inability of petals to store high concentrations of carotenoids other than xanthophylls and by degradation of b-carotene, which accumulates as a result of the wf mutation but is not due to altered expression of genes in the biosynthetic pathway.

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Toward an Understanding of the Mechanism of Nonphotochemical Quenching in Green Plants

Cited by 300 publications

References 70 publications

The xanthophyll cycle pool size controls the kinetics of non‐photochemical quenching in Arabidopsis thaliana

The xanthophyll cycle pool size controls the kinetics of non‐photochemical quenching in Arabidopsis thaliana

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

A Chromoplast-Specific Carotenoid Biosynthesis Pathway Is Revealed by Cloning of the Tomato white-flower Locus

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