A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio
<p>Abstract</p> <p>Background</p> <p>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...
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| Format: | Article |
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BMC
2012-04-01
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| Series: | BMC Plant Biology |
| Online Access: | http://www.biomedcentral.com/1471-2229/12/50 |
| _version_ | 1818833265428004864 |
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| author | Fiore Alessia Dall'Osto Luca Cazzaniga Stefano Diretto Gianfranco Giuliano Giovanni Bassi Roberto |
| author_facet | Fiore Alessia Dall'Osto Luca Cazzaniga Stefano Diretto Gianfranco Giuliano Giovanni Bassi Roberto |
| author_sort | Fiore Alessia |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>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 <it>chy1chy2lut5 </it>mutant is almost completely depleted in β-xanthophylls.</p> <p>Results</p> <p>Here we report on the quadruple <it>chy1chy2lut2lut5 </it>mutant, additionally carrying the <it>lut2 </it>mutation (affecting lycopene ε-cyclase). This genotype lacks lutein and yet it shows a compensatory increase in β-xanthophylls with respect to <it>chy1chy2lut5 </it>mutant. Mutant plants show an even stronger photosensitivity than <it>chy1chy2lut5</it>, 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 <it>chy1chy2lut2lut5 </it>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.</p> <p>Conclusions</p> <p>The physiological and biochemical phenotype of the <it>chy1chy2lut2lut5 </it>mutant shows that (i) LUT1/CYP97C1 protein reveals a major β-carotene hydroxylase activity <it>in vivo </it>when depleted in its preferred substrate α-carotene; (ii) xanthophylls are needed for normal level of Photosystem I and LHCII accumulation.</p> |
| first_indexed | 2024-12-19T02:16:11Z |
| format | Article |
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| issn | 1471-2229 |
| language | English |
| last_indexed | 2024-12-19T02:16:11Z |
| publishDate | 2012-04-01 |
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| spelling | doaj.art-670a345550b44749bf7b95224e8cda242022-12-21T20:40:24ZengBMCBMC Plant Biology1471-22292012-04-011215010.1186/1471-2229-12-50A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratioFiore AlessiaDall'Osto LucaCazzaniga StefanoDiretto GianfrancoGiuliano GiovanniBassi Roberto<p>Abstract</p> <p>Background</p> <p>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 <it>chy1chy2lut5 </it>mutant is almost completely depleted in β-xanthophylls.</p> <p>Results</p> <p>Here we report on the quadruple <it>chy1chy2lut2lut5 </it>mutant, additionally carrying the <it>lut2 </it>mutation (affecting lycopene ε-cyclase). This genotype lacks lutein and yet it shows a compensatory increase in β-xanthophylls with respect to <it>chy1chy2lut5 </it>mutant. Mutant plants show an even stronger photosensitivity than <it>chy1chy2lut5</it>, 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 <it>chy1chy2lut2lut5 </it>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.</p> <p>Conclusions</p> <p>The physiological and biochemical phenotype of the <it>chy1chy2lut2lut5 </it>mutant shows that (i) LUT1/CYP97C1 protein reveals a major β-carotene hydroxylase activity <it>in vivo </it>when depleted in its preferred substrate α-carotene; (ii) xanthophylls are needed for normal level of Photosystem I and LHCII accumulation.</p>http://www.biomedcentral.com/1471-2229/12/50 |
| spellingShingle | Fiore Alessia Dall'Osto Luca Cazzaniga Stefano Diretto Gianfranco Giuliano Giovanni Bassi Roberto A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio BMC Plant Biology |
| title | A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio |
| title_full | A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio |
| title_fullStr | A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio |
| title_full_unstemmed | A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio |
| title_short | A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio |
| title_sort | quadruple mutant of arabidopsis reveals a β carotene hydroxylation activity for lut1 cyp97c1 and a regulatory role of xanthophylls on determination of the psi psii ratio |
| url | http://www.biomedcentral.com/1471-2229/12/50 |
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