Comparison of violaxanthin de-epoxidation from the stroma and lumen sides of isolated thylakoid membranes from Arabidopsis : implications for the mechanism of de-epoxidation

Macko, S. N.; Wehner, Antje; Jahns, Peter

doi:10.1007/s00425-002-0848-8

Cited by 23 publications

(16 citation statements)

References 36 publications

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“…Since this effect corresponds to the function typically attributed to vitamin E both in plant and animal membranes, the functional redundancy found in this study between zeaxanthin and vitamin E is not very surprising. Operation of the xanthophyll cycle has been assumed to involve binding and release of violaxanthin from pigment binding complexes (Morosinotto et al, 2002(Morosinotto et al, , 2003, diffusion of the xanthophyll molecules within the thylakoid membrane (Macko et al, 2002), and conversion of violaxanthin to zeaxanthin by the deepoxidase enzyme in the lipid (monogalactosyldiacylglycerol) phase (Hieber et al, 2004). Therefore, the zeaxanthin molecules formed in the xanthophyll cycle are initially present in the thylakoid lipid phase or at the interface lipid light-harvesting complex where they could supplement the antioxidative action of vitamin E (Havaux, 1998), so that removal of both compounds in vte1 npq1 resulted in almost complete deprivation of lipophilic antioxidants from the thylakoid membrane.…”

Section: Zeaxanthin and Vitamin E Have Overlapping Functionsmentioning

confidence: 99%

Vitamin E Protects against Photoinhibition and Photooxidative Stress in Arabidopsis thaliana

et al. 2005

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Vitamin E is considered a major antioxidant in biomembranes, but little evidence exists for this function in plants under photooxidative stress. Leaf discs of two vitamin E mutants, a tocopherol cyclase mutant (vte1) and a homogentisate phytyl transferase mutant (vte2), were exposed to high light stress at low temperature, which resulted in bleaching and lipid photodestruction. However, this was not observed in whole plants exposed to long-term high light stress, unless the stress conditions were extreme (very low temperature and very high light), suggesting compensatory mechanisms for vitamin E deficiency under physiological conditions. We identified two such mechanisms: nonphotochemical energy dissipation (NPQ) in photosystem II (PSII) and synthesis of zeaxanthin. Inhibition of NPQ in the double mutant vte1 npq4 led to a marked photoinhibition of PSII, suggesting protection of PSII by tocopherols. vte1 plants accumulated more zeaxanthin in high light than the wild type, and inhibiting zeaxanthin synthesis in the vte1 npq1 double mutant resulted in PSII photoinhibition accompanied by extensive oxidation of lipids and pigments. The single mutants npq1, npq4, vte2, and vte1 showed little sensitivity to the stress treatments. We conclude that, in cooperation with the xanthophyll cycle, vitamin E fulfills at least two different functions in chloroplasts at the two major sites of singlet oxygen production: preserving PSII from photoinactivation and protecting membrane lipids from photooxidation.

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Section: Zeaxanthin and Vitamin E Have Overlapping Functionsmentioning

confidence: 99%

Vitamin E Protects against Photoinhibition and Photooxidative Stress in Arabidopsis thaliana

et al. 2005

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“…Finally, the close packing of the proteins in the grana region of the membranes (where PSII is located) is likely to restrict diffusion of Vx in the lipid phase. Xanthophyll diffusion has been supposed to be rate-limiting for the de-epoxidation reactions in vivo (58). Thus, under in vivo conditions not only the release of Vx from the carotenoid binding sites (which is determined by the binding affinity of Vx to the respective binding sites in the different antenna proteins) but also the overall organization of the antenna proteins in the membrane will determine the extent and kinetics of de-epoxidation in leaves.…”

Section: De-epoxidation In Recombinant Lhcb5mentioning

confidence: 99%

De-epoxidation of Violaxanthin in the Minor Antenna Proteins of Photosystem II, LHCB4, LHCB5, and LHCB6

Wehner

Grasses

Jahns

2006

Journal of Biological Chemistry

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The conversion of violaxanthin to zeaxanthin is essentially required for the pH-regulated dissipation of excess light energy in the antenna of photosystem II. Violaxanthin is bound to each of the antenna proteins of both photosystems. Former studies with recombinant Lhcb1 and different Lhca proteins implied that each antenna protein contributes specifically to violaxanthin conversion related to protein-specific affinities of the different violaxanthin binding sites. We investigated the violaxanthin de-epoxidation in the minor antenna proteins of photosystem II, Lhcb4 -6. Recombinant proteins were reconstituted with different xanthophyll mixtures to study the conversion of violaxanthin at different xanthophyll binding sites in these proteins. The extent and kinetics of violaxanthin de-epoxidation were found to be dependent on the respective protein and, for each protein, also on the binding site of violaxanthin. In particular, violaxanthin bound to Lhcb4 was nearly inconvertible for de-epoxidation, whereas violaxanthin bound to Lhcb5 was fully convertible but with slow kinetics. Lhcb6 exhibited heterogeneous violaxanthin conversion characteristics, which could be assigned to different populations of reconstituted Lhcb6 complexes with respect to violaxanthin binding sites. The results support the proposed different binding affinities of violaxanthin to the three putative violaxanthin binding sites (V1, N1, and L2) in antenna proteins. Under consideration of former studies with Lhcb1 and Lhca proteins, the data imply that violaxanthin bound to the V1 and N1 binding site of antenna proteins is easily accessible for de-epoxidation in all antenna proteins, whereas violaxanthin bound to L2 is either only slowly or not convertible to zeaxanthin, depending on the respective protein.

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“…Studies of the characteristics of Vx deepoxidation from the stroma side of the thylakoid membrane indicate that the VxDE converts Vx in the lipid matrix and not at the protein (27,28). The comparison of the temperature dependence of Vx de-epoxidation from both sides of the thylakoid membrane led further to the conclusion that the release of Vx from the carotenoid binding sites and/or the diffusion of Vx in the lipid matrix might be the rate-limiting reaction of the de-epoxidation reactions (28). Thus, the conversion of proteinbound Vx to Zx would require the following: (i) the release of Vx into the lipid phase; (ii) the diffusion of Vx to the VxDE; (iii) the de-epoxidation of Vx in the lipid matrix; and (iv) the rebinding of Zx to the protein.…”

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confidence: 99%

De-epoxidation of Violaxanthin in Light-harvesting Complex I Proteins

Wehner

Storf

Jahns

et al. 2004

Journal of Biological Chemistry

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The conversion of violaxanthin (Vx) to zeaxanthin (Zx) in the de-epoxidation reaction of the xanthophyll cycle plays an important role in the protection of chloroplasts against photooxidative damage. Vx is bound to the antenna proteins of both photosystems. In photosystem II, the formation of Zx is essential for the pH-dependent dissipation of excess light energy as heat. The function of Zx in photosystem I is still unclear. In this work we investigated the de-epoxidation characteristics of light-harvesting complex proteins of photosystem I (LHCI) under in vivo and in vitro conditions. Recombinant LHCI (Lhcal-4) proteins were reconstituted with Vx and lutein, and the convertibility of Vx was studied in an in vitro assay using partially purified Vx de-epoxidase isolated from spinach thylakoids. All four LHCI proteins exhibited unique de-epoxidation characteristics. An almost complete Vx conversion to Zx was observed only in Lhca3, whereas Zx formation in the other LHCI proteins decreased in the order Lhca4 > Lhca1 > Lhca2. Most likely, these differences in Vx de-epoxidation were related to the different accessibility of the respective carotenoid binding sites in the distinct antenna proteins. The results indicate that Vx bound to site V1 and N1 is easily accessible for de-epoxidation, whereas Vx bound to L2 is only partially and/or with the slower kinetics convertible to Zx. The de-epoxidation properties determined for the monomeric recombinant proteins were consistent with those obtained for isolated native LHCI-730 and LHCI-680 in the same in vitro assay and the de-epoxidation state found under in vivo conditions in native LHCIs.

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Comparison of violaxanthin de-epoxidation from the stroma and lumen sides of isolated thylakoid membranes from Arabidopsis : implications for the mechanism of de-epoxidation

Cited by 23 publications

References 36 publications

Vitamin E Protects against Photoinhibition and Photooxidative Stress in Arabidopsis thaliana

Vitamin E Protects against Photoinhibition and Photooxidative Stress in Arabidopsis thaliana

De-epoxidation of Violaxanthin in the Minor Antenna Proteins of Photosystem II, LHCB4, LHCB5, and LHCB6

De-epoxidation of Violaxanthin in Light-harvesting Complex I Proteins

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