Functional characterization of CmCCD1, a carotenoid cleavage dioxygenase from melon
Functional characterization of CmCCD1, a carotenoid cleavage dioxygenase from melon
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DOI：
10.1016/j.phytochem.2006.02.009
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发表时间：
2006-08-01
期刊：
影响因子：
3.8
通讯作者：
Lewinsohn, Efraim
中科院分区：
文献类型：
--
作者：
Ibdah, Mwafaq;Azulay, Yaniv;Lewinsohn, Efraim
类胡萝卜素是营养上重要的四萜类色素，其在氧化裂解时产生脱辅基类胡萝卜素（去甲异戊二烯）芳香挥发物。β-胡萝卜素是橙肉甜瓜（Cucumis梅洛L.）品种，达到高达50微克/克FW的水平。淡绿色绿色和白色品种的含量低得多（0-10 μ g/g FW）。同时，β-紫罗兰酮，β-胡萝卜素的9，10裂解产物，存在于积累β-胡萝卜素的橙色果肉甜瓜品种中（12-33 ng/g FW），并且在浅绿色和白色果肉品种中以低得多的水平（0-5 ng/g FW）存在。在注释的甜瓜果实EST数据库中搜索负责将β-胡萝卜素裂解成β-紫罗兰酮的基因puC 1，得到与其他植物类胡萝卜素裂解双加氧酶基因高度相似（84%）的序列（CmCCD 1）。为了测试其功能，该克隆在大肠杆菌菌株中过表达，这些菌株先前被工程改造以产生不同的类胡萝卜素。我们在这里表明，CmCCD 1基因产物在位置9，10和9 '，10'切割类胡萝卜素，从八氢番茄红素生成香叶基丙酮;从番茄红素生成假紫罗兰酮;从β-胡萝卜素生成β-紫罗兰酮，以及从δ-胡萝卜素生成α-紫罗兰酮和假紫罗兰酮。CmCCD 1基因表达上调果实发育后，无论是在橙子，浅绿色和白色甜瓜品种，尽管缺乏脱辅基类胡萝卜素挥发物。因此，甜瓜果实中P-紫罗兰酮的积累可能受到类胡萝卜素底物的限制。(c)2006爱思唯尔有限公司保留所有权利。
Carotenoids are nutritionally important tetraterpenoid pigments that upon oxidative cleavage give rise to apocarotenoid (norisoprene) aroma volatiles. beta-Carotene is the predominant pigment in orange-fleshed melon (Cucumis melo L.) varieties, reaching levels of up to 50 mu g/g FW. Pale green and white cultivars have much lower levels (0-10 mu g/g FW). In parallel, beta-ionone, the 9,10 cleavage product of beta-carotene, is present (12-33 ng/g FW) in orange-fleshed melon varieties that accumulate beta-carotene, and in much lower levels (0-5 ng/g FW) in pale green and white fleshed varieties. A search for a gene putatively responsible for the cleavage of P-carotene into P-ionone was carried out in annotated melon fruit EST databases yielding a sequence (CmCCD1) highly similar (84%) to other plant carot enoid cleavage dioxygenase genes. To test its function, the clone was overexpressed in Escherichia coli strains previously engineered to produce different carotenoids. We show here that the CmCCD1 gene product cleaves carotenoids at positions 9,10 and 9', 10', generating geranylacetone from phytoene; pseudoionone from lycopene; beta-ionone from beta-carotene, as well as alpha-ionone and pseudoionone from delta-carotene. CmCCD1 gene expression is upregulated upon fruit development both in orange, pale-green and white melon varieties, despite the lack of apocarotenoid volatiles in the later. Thus, the accumulation of P-ionone in melon fruit is probably limited by the availability of carotenoid substrate. (c) 2006 Elsevier Ltd. All rights reserved.