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Lutein is needed for efficient chlorophyll triplet quenching in the major LHCII antenna complex of higher plants and effective photoprotection in vivo under strong light

TitleLutein is needed for efficient chlorophyll triplet quenching in the major LHCII antenna complex of higher plants and effective photoprotection in vivo under strong light
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2006
AuthorsDall'Osto, L., Lico Chiara, Alric J., Giuliano Giovanni, Havaux M., and Bassi R.
JournalBMC Plant Biology
Volume6
ISSN14712229
KeywordsBiological, cold, Cold Temperature, Electrophoresis, Embryophyta, light, Lutein, metabolism, oxidation reduction reaction, Oxidation-Reduction, photosynthesis, Photosynthetic Reaction Center Complex Proteins, physiology, pigment, Pigments, Plant, Plants, Polyacrylamide Gel, polyacrylamide gel electrophoresis, reactive oxygen metabolite, Reactive Oxygen Species, xanthophyll
Abstract

Background: Lutein is the most abundant xanthophyll in the photosynthetic apparatus of higher plants. It binds to site L1 of all Lhc proteins, whose occupancy is indispensable for protein folding and quenching chlorophyll triplets. Thus, the lack of a visible phenotype in mutants lacking lutein has been surprising. Results: We have re-assessed the lut2.1 phenotypes through biochemical and spectroscopic methods. Lhc proteins from the lut2.1 mutant compensate the lack of lutein by binding violaxanthin in sites L1 and L2. This substitution reduces the capacity for regulatory mechanisms such as NPQ, reduces antenna size, induces the compensatory synthesis of Antheraxanthin + Zeaxanthin, and prevents the trimerization of LHCII complexes. In vitro reconstitution shows that the lack of lutein per se is sufficient to prevent trimerization. lut2.1 showed a reduced capacity for state I - state II transitions, a selective degradation of Lhcb1 and 2, and a higher level of photodamage in high light and/or low temperature, suggesting that violaxanthin cannot fully restore chlorophyll triplet quenching. In vitro photobleaching experiments and time-resolved spectroscopy of carotenoid triplet formation confirmed this hypothesis. The npq1lut2.1 double mutant, lacking both zeaxanthin and lutein, is highly susceptible to light stress. Conclusion: Lutein has the specific property of quenching harmful 3Chl* by binding at site L1 of the major LHCII complex and of other Lhc proteins of plants, thus preventing ROS formation. Substitution of lutein by violaxanthin decreases the efficiency of 3Chl* quenching and causes higher ROS yield. The phenotype of lut2.1 mutant in low light is weak only because rescuing mechanisms of photoprotection, namely zeaxanthin synthesis, compensate for the ROS production. We conclude that zeaxanthin is effective in photoprotection of plants lacking lutein due to the multiple effects of zeaxanthin in photoprotection, including ROS scavenging and direct quenching of Chl fluorescence by binding to the L2 allosteric site of Lhc proteins. © 2006 Dall'Osto et al; licensee BioMed Central Ltd.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-33846572393&doi=10.1186%2f1471-2229-6-32&partnerID=40&md5=5bc7a69c8a044a875947e6cd240da07e
DOI10.1186/1471-2229-6-32
Citation KeyDall'Osto2006