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Different roles of α- and β-branch xanthophylls in photosystem assembly and photoprotection

TitoloDifferent roles of α- and β-branch xanthophylls in photosystem assembly and photoprotection
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2007
AutoriDall'Osto, L., Fiore Alessia, Cazzaniga S., Giuliano Giovanni, and Bassi R.
RivistaJournal of Biological Chemistry
Volume282
Paginazione35056-35068
ISSN00219258
Parole chiaveArabidopsis, article, beta carotene, Binding Sites, Complexation, Electron microscopy, fluorescence, gel electrophoresis, Hydrogen-Ion Concentration, Immunoblotting, in vivo study, light, Light harvesting, Light-Harvesting Protein Complexes, Lipid peroxidation, mutation, neoxanthin, nonhuman, Oxidative stress, Oxygen, pH measurement, Photochemistry, photoreactivity, photosynthesis, Photosystem II Protein Complex, Photosystems, Pigments, plant physiology, Plants (botany), priority journal, protein assembly, protein function, Protein Structure, protein synthesis, Proteins, Spectrometry, Stoichiometry, Thylakoids, violaxanthin, xanthophyll, Xanthophylls, Zeaxanthin
Abstract

Xanthophylls (oxygenated carotenoids) are essential components of the plant photosynthetic apparatus, where they act in photosystem assembly, light harvesting, and photoprotection. Nevertheless, the specific function of individual xanthophyll species awaits complete elucidation. In this work, we analyze the photosynthetic phenotypes of two newly isolated Arabidopsis mutants in carotenoid biosynthesis containing exclusively α-branch (chy1chy2lut5) or β-branch (chy1chy2lut2) xanthophylls. Both mutants show complete lack of qE, the rapidly reversible component of nonphotochemical quenching, and high levels of photoinhibition and lipid peroxidation under photooxidative stress. Both mutants are much more photosensitive than npq1lut2, which contains high levels of viola- and neoxanthin and a higher stoichiometry of light-harvesting proteins with respect to photosystem II core complexes, suggesting that the content in light-harvesting complexes plays an important role in photoprotection. In addition, chy1chy2lut5, which has lutein as the only xanthophyll, shows unprecedented photosensitivity even in low light conditions, reduced electron transport rate, enhanced photobleaching of isolated LHCII complexes, and a selective loss of CP26 with respect to chy1chy2lut2, highlighting a specific role of β-branch xanthophylls in photoprotection and in qE mechanism. The stronger photosystem II photoinhibition of both mutants correlates with the higher rate of singlet oxygen production from thylakoids and isolated light-harvesting complexes, whereas carotenoid composition of photosystem II core complex was not influential. In depth analysis of the mutant phenotypes suggests that α-branch (lutein) and β-branch (zeaxanthin, violaxanthin, and neoxanthin) xanthophylls have distinct and complementary roles in antenna protein assembly and in the mechanisms of photoprotection. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-36849068798&doi=10.1074%2fjbc.M704729200&partnerID=40&md5=f5cc5151e965afa01466f3e5c4941d8e
DOI10.1074/jbc.M704729200
Citation KeyDall'Osto200735056