Ascorbate-independent carotenoid de-epoxidation in intact spinach chloroplasts

Sokolove, Patricia M.; Marsho, Thomas V.

doi:10.1016/0005-2728(76)90088-8

Cited by 23 publications

(14 citation statements)

References 19 publications

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“…l), thus indicating that NADPH does not affect the lumen pH. As reported previously, DTT does not affect dpH [7] and does not reverse the preformed SV, in absence of NADPH [8,12]. Our results, aside from showing that NPQ depends on epoxidation-deepoxidation cycle activity, have other important and interesting implication.…”

Section: Resultssupporting

confidence: 80%

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Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH

1994

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The xanthophyll cycle apparently aids the photoprotection of photosystem II by regulating the nonradiative dissipation of excess absorbed light energy as heat. However, it is a controversial question whether the resulting nonphotochemical quenching is soley dependent on xanthophyll cycle activity or not. The xanthophyll cycle consists of two enzymic reactions, namely deepoxidation of the diepoxide violaxanthin to the epoxide-free zeaxanthin and the much slower, reverse process of epoxidation. While deepoxidation requires a transthylakoid pH gradient (dpH), epoxidation can proceed irrespective of a dpH. Herein, we compared the extent and kinetics of deepoxidation and epoxidation to the changes in fluorescence in the presence of a light-induced thylakoid dpH. We show that epoxidation reverses fluorescence quenching without affecting thylakoid dpH. These results suggest that epoxidase activity reverses quenching by removing deepoxidized xanthophyll cycle pigments from quenching complexes and converting them to a nonquenching form. The transmembrane organization of the xanthophyll cycle influences the localization and the availability of deepoxidized xanthophylls is to support nonphotochemical quenching capacity. The results confirm the view that rapidly reversible nonphotochemical quenching is dependent on deepoxidized xanthophyll.

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Section: Resultssupporting

confidence: 80%

“…The sulfhydryl reagent dithiothreitol (DTT) inhibits deepoxidation without affecting light-induced or ATP hydrolysis-induced proton pumping [6,7,8]. Deepoxidation at ambient temperatures usually takes less than 10 min to reach completion.…”

Section: Epoxidationmentioning

confidence: 99%

Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH

1994

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“…DTT acts on the de-epoxidase without a¡ecting lumen acidi¢cation [19]. DTT also inhibits the DD de-epoxidase in diatoms [20].…”

Section: Resultsmentioning

confidence: 99%

In diatoms, a transthylakoid proton gradient alone is not sufficient to induce a non‐photochemical fluorescence quenching

2002

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Non-photochemical £uorescence quenching (NPQ) in diatoms is associated with a xanthophyll cycle involving diadinoxanthin (DD) and its de-epoxidized form, diatoxanthin (DT). In higher plants, an obligatory role of de-epoxidized xanthophylls in NPQ remains controversial and the presence of a transthylakoid proton gradient (v vpH) alone may induce NPQ. We used inhibitors to alter the amplitude of v vpH and/or DD de-epoxidation, and coupled NPQ. No v vpH-dependent quenching was detected in the absence of DT. In diatoms, both v vpH and DT are required for NPQ. The binding of DT to protonated antenna sites could be obligatory for energy dissipation. ß

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“…Only a few lumenal proteins with known thiol-dependent enzymatic activities have been identified. Examples of such are violaxanthin deepoxidase, an enzyme involved in dissipating excess light (Yamamoto and Kamite, 1972;Sokolove and Marsho, 1976), STT7/STN7, a kinase involved in adaptation to changes in light intensity (Depè ge et al, 2003;Lemeille et al, 2009), and FKBP13, a prolyl isomerase postulated to act as a foldase for the Rieske protein (Gupta et al, 2002;Gopalan et al, 2004). It has now become apparent that thioldisulfide chemistry is a catalyzed process not only restricted to bacterial energy-transducing membranes but operating also on the lumenal side of the thylakoid membrane.…”

Section: The Redox Activity Of Lto1 Is Required For the Assembly Of Psiimentioning

confidence: 99%

Lumen Thiol Oxidoreductase1, a Disulfide Bond-Forming Catalyst, Is Required for the Assembly of Photosystem II inArabidopsis

et al. 2011

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Here, we identify Arabidopsis thaliana Lumen Thiol Oxidoreductase1 (LTO1) as a disulfide bond-forming enzyme in the thylakoid lumen. Using topological reporters in bacteria, we deduced a lumenal location for the redox active domains of the protein. LTO1 can partially substitute for the proteins catalyzing disulfide bond formation in the bacterial periplasm, which is topologically equivalent to the plastid lumen. An insertional mutation within the LTO1 promoter is associated with a severe photoautotrophic growth defect. Measurements of the photosynthetic activity indicate that the lto1 mutant displays a limitation in the electron flow from photosystem II (PSII). In accordance with these measurements, we noted a severe depletion of the structural subunits of PSII but no change in the accumulation of the cytochrome b 6 f complex or photosystem I. In a yeast two-hybrid assay, the thioredoxin-like domain of LTO1 interacts with PsbO, a lumenal PSII subunit known to be disulfide bonded, and a recombinant form of the molecule can introduce a disulfide bond in PsbO in vitro. The documentation of a sulfhydryl-oxidizing activity in the thylakoid lumen further underscores the importance of catalyzed thiol-disulfide chemistry for the biogenesis of the thylakoid compartment.

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Ascorbate-independent carotenoid de-epoxidation in intact spinach chloroplasts

Cited by 23 publications

References 19 publications

Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH

Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH

In diatoms, a transthylakoid proton gradient alone is not sufficient to induce a non‐photochemical fluorescence quenching

Lumen Thiol Oxidoreductase1, a Disulfide Bond-Forming Catalyst, Is Required for the Assembly of Photosystem II inArabidopsis

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