Molecular and functional characterization of a novel chromoplast-specific lycopene beta-cyclase from Citrus and its relation to lycopene accumulation.
Molecular and functional characterization of a novel chromoplast-specific lycopene beta-cyclase from Citrus and its relation to lycopene accumulation.
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DOI：
10.1093/jxb/erp048
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发表时间：
2009
影响因子：
6.9
通讯作者：
Rodrigo MJ
中科院分区：
文献类型：
--
作者：
Alquézar B;Zacarías L;Rodrigo MJ
类胡萝卜素是柑橘类水果着色的主要色素。由番茄红素β-环化酶（β-LCY）催化的番茄红素β-环化似乎是类胡萝卜素途径的关键调控步骤。本研究从柑桔果实（Citrus sinensis）中分离了两个β-LCYs，分别命名为Csβ-LCY1和Csβ-LCY2，并通过功能分析证实了其编码蛋白的活性。Csβ-LCY1在果实成熟过程中表达水平较低，且相对稳定；而Csβ-LCY2在柑桔果皮和果肉中均有显着的色质体特异性表达和诱导，并与β、β-叶黄素积累同步进行。研究了cs - β- lcy2在红葡萄柚等柑橘类植物番茄红素积累中的潜在作用。研究了cs - β- lcy2等7个类胡萝卜素生物合成基因在高番茄红素积累柚子星红宝石果皮和果肉中的表达，并与普通脐橙进行了比较。在星红宝石中，果实成熟过程中番茄红素的积累与脐橙中β-LCY2和β-CHX基因的表达显著降低有关。此外，从两个基因型中分离到β-LCY2的两个不同等位基因：β-LCY2a和β-LCY2b，功能分析表明等位基因b的番茄红素β-环化酶活性几乎为零。有趣的是，星红宝石葡萄柚在果实成熟过程中主要表达无功能的β-LCY2b等位基因，而脐橙则更倾向于表达功能等位基因。提示，β-LCY2基因编码活性改变酶的多种等位基因的存在和不同转录量的积累可能是红葡萄柚类胡萝卜素合成参与番茄红素积累的另一个调控机制。
Carotenoids are the main pigments responsible of the colouration of Citrus fruits. The β-cyclization of lycopene, catalysed by the lycopene β-cyclases (β-LCY), seems to be a key regulatory step of the carotenoid pathway. In the present study, two β-LCYs from orange fruits (Citrus sinensis), named Csβ-LCY1 and Csβ-LCY2 have been isolated and the activity of the encoded proteins was demonstrated by functional analysis. Csβ-LCY1 was expressed at low levels and remained relatively constant during fruit ripening while Csβ-LCY2 showed a chromoplast-specific expression and a marked induction in both peel and pulp of orange fruits in parallel with the accumulation of β,β-xanthophylls. The potential involvement of Csβ-LCY2 in the accumulation of lycopene, characteristic of some Citrus species such as red grapefruits, was investigated. Expression of Csβ-LCY2 and another seven carotenoid biosynthetic genes were studied in the peel and pulp of the high lycopene-accumulating grapefruit, Star Ruby, and compared with those of ordinary Navel orange. In Star Ruby, the accumulation of lycopene during fruit maturation was associated with a substantial reduction in the expression of both β-LCY2 and β-CHX genes with respect to Navel orange. Moreover, two different alleles of β-LCY2: β-LCY2a and β-LCY2b were isolated from both genotypes, and functional assays demonstrated that the lycopene β-cyclase activity of the allele b was almost null. Interestingly, Star Ruby grapefruit predominantly expressed the unfunctional β-LCY2b allele during fruit ripening whereas Navel oranges preferably expressed the functional allele. It is suggested that the presence of diverse alleles of the β-LCY2 gene, encoding enzymes with altered activity, with different transcript accumulation may be an additional regulatory mechanism of carotenoid synthesis involved in the accumulation of lycopene in red grapefruits.
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影响因子：
6.4
作者：
Inoue, Kentaro;Furbee, Kendra J.;Ikoma, Yoshinori
通讯作者：
Ikoma, Yoshinori
影响因子：
6.1
作者：
Alos, Enriqueta;Cercos, Manuel;Talon, Manuel
通讯作者：
Talon, Manuel
影响因子：
11.6
作者：
Cunningham, FX;Pogson, B;Gantt, E
通讯作者：
Gantt, E
DOI：
10.1006/bbrc.1994.1350
发表时间：
1994-03-30
影响因子：
3.1
作者：
DERUERE, J;BOUVIER, F;KUNTZ, M
通讯作者：
KUNTZ, M
影响因子：
6.1
作者：
Fanciullino, Anne-Laure;Dhuique-Mayer, Claudie;Ollitrault, Patrick
通讯作者：
Ollitrault, Patrick