Significance of the lipid phase in the dynamics and functions of the xanthophyll cycle as revealed by PsbS overexpression in tobacco and in-vitro de-epoxidation in monogalactosyldiacyglycerol micelles

The dynamics of the xanthophyll cycle relative to non-photochemical quenching (NPQ) were examined in tobacco plants overexpressing violaxanthin de-epoxidase (VDE), PsbS and PsbS+VDE for effects on NPQ and violaxanthin (V) de-epoxidation over a range of light intensities. Induction of de-epoxidation...

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Published inPlant and cell physiology Vol. 45; no. 1; pp. 92 - 102
Main Authors Hieber, A.D, Kawabata, O, Yamamoto, H.Y
Format Journal Article
LanguageEnglish
Published 2004
Subjects
Arabidopsis thaliana
biochemical pathways
epoxides
gene overexpression
light
light harvesting complex
lipids
lutein
monogalactosyldiacylglycerol
Nicotiana tabacum
non-photochemical quenching
oxidoreductases
photosynthetic reaction centers
photosystem II
plant proteins
tobacco
transgenes
transgenic plants
violaxanthin
violaxanthin de-epoxidase
zeaxanthin
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Summary:The dynamics of the xanthophyll cycle relative to non-photochemical quenching (NPQ) were examined in tobacco plants overexpressing violaxanthin de-epoxidase (VDE), PsbS and PsbS+VDE for effects on NPQ and violaxanthin (V) de-epoxidation over a range of light intensities. Induction of de-epoxidation and NPQ increased in overexpressed VDE and PsbS plants, respectively. Surprisingly, under low light, overexpressing PsbS enhanced de-epoxidation in addition to NPQ. The effect was hypothesized as due to PsbS binding zeaxanthin (Z) or inducing the binding of Z within the quenching complex, thus shifting the equilibrium toward higher de-epoxidation states. Studies in model systems show that Z can stereospecifically inhibit VDE activity against violaxanthin. This effect, observed under conditions of limiting lipid concentration, was interpreted as product feedback inhibition. These results support the hypothesis that the capacity of the thylakoid lipid phase for xanthophylls is limited and modulates xanthophyll-cycle activity, in conjunction with the release of V and binding of Z by pigment-binding proteins. These modulating factors are incorporated into a lipid-matrix model that has elements of a signal transduction system wherein the light-generated protons are the signal, VDE the signal receptor, Z the secondary messenger, the lipid phase the transduction network, and Z-binding proteins the targets.
ISSN:0032-0781
1471-9053