Journal Article

PreJuSER-22168

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png A quadruple mutant of Arabidopsis reveals a novel activity for LUT1/CYP97C1 in carotene hydroxylation and a regulatory role of xanthophylls on determination of the PSI/PSII ratio

Fiore, A. ; Dall'Osto, L. ; Cazzaniga, S. ; Diretto, G. ; Giuliano, G. ; Bassi, R.FZJ*

2012
BioMed Central London

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Please use a persistent id in citations: http://hdl.handle.net/2128/7510  doi:10.1186/1471-2229-12-50

Abstract: Xanthophylls are oxygenated carotenoids playing an essential role as structural components of the photosynthetic apparatus. Xanthophylls contribute to the assembly and stability of light-harvesting complex, to light absorbance and to photoprotection. The first step in xanthophyll biosynthesis from α- and β-carotene is the hydroxylation of ε- and β-rings, performed by both non-heme iron oxygenases (CHY1, CHY2) and P450 cytochromes (LUT1/CYP97C1, LUT5/CYP97A3). The Arabidopsis triple chy1chy2lut5 mutant is almost completely depleted in β-xanthophylls.Here we report on the quadruple chy1chy2lut2lut5 mutant, additionally carrying the lut2 mutation (affecting lycopene ε-cyclase). This genotype lacks lutein and yet it shows a compensatory increase in β-xanthophylls with respect to chy1chy2lut5 mutant. Mutant plants show an even stronger photosensitivity than chy1chy2lut5, a complete lack of qE, the rapidly reversible component of non-photochemical quenching, and a peculiar organization of the pigment binding complexes into thylakoids. Biochemical analysis reveals that the chy1chy2lut2lut5 mutant is depleted in Lhcb subunits and is specifically affected in Photosystem I function, showing a deficiency in PSI-LHCI supercomplexes. Moreover, by analyzing a series of single, double, triple and quadruple Arabidopsis mutants in xanthophyll biosynthesis, we show a hitherto undescribed correlation between xanthophyll levels and the PSI-PSII ratio. The decrease in the xanthophyll/carotenoid ratio causes a proportional decrease in the LHCII and PSI core levels with respect to PSII.The physiological and biochemical phenotype of the chy1chy2lut2lut5 mutant shows that (i) LUT1/CYP97C1 protein reveals a major β-carotene hydroxylase activity in vivo when depleted in its preferred substrate α-carotene; (ii) xanthophylls are needed for normal level of Photosystem I and LHCII accumulation.

Keyword(s): Arabidopsis: genetics (MeSH) ; Arabidopsis: metabolism (MeSH) ; Arabidopsis Proteins: genetics (MeSH) ; Arabidopsis Proteins: metabolism (MeSH) ; Mutation (MeSH) ; Photosystem I Protein Complex: metabolism (MeSH) ; Photosystem II Protein Complex: metabolism (MeSH) ; Xanthophylls: metabolism (MeSH) ; beta Carotene: metabolism (MeSH) ; Arabidopsis Proteins ; Photosystem I Protein Complex ; Photosystem II Protein Complex ; Xanthophylls ; beta Carotene ; J

Note: Work supported by the Italian ministry of Research, special fund for basic research (PRIN 2008XB774B), and by the European Commission, Metapro project.

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Contributing Institute(s):

1. Pflanzenwissenschaften (IBG-2)

Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2012
Notes: erscheint nur online

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