Cloning and characterization of genes involved in nostoxanthin biosynthesis of Sphingomonas elodea ATCC 31461.
Cloning and characterization of genes involved in nostoxanthin biosynthesis of Sphingomonas elodea ATCC 31461.
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DOI：
10.1371/journal.pone.0035099
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Gao H
中科院分区：
文献类型：
--
作者：
Zhu L;Wu X;Li O;Qian C;Gao H
大多数鞘氨醇单胞菌都合成黄色类胡萝卜素nostoxantin。然而，这些物种类胡萝卜素的生物合成途径尚不清楚。在本研究中，我们从结冷胶产生菌βelodea atcc 31461中克隆并鉴定了一个类胡萝卜素生物合成基因簇，该基因簇包含四个类胡萝卜素合成基因(crtG、crty、crtI和crtB)和一个位于簇外的类胡萝卜素羟基酶基因(CrtZ)。这些基因中的每一个都被失活，通过对基因敲除突变体中积累的中间产物进行层析和光谱分析，证实了每个基因的生化功能。此外，编码2，2‘-β-羟基酶的crtG基因和编码β-胡萝卜素羟基酶的crtZ基因都与β-胡萝卜素的羟化有关，通过与产生不同类胡萝卜素的大肠杆菌的互补研究，证实了这两个基因的存在。在玉米黄质和β-胡萝卜素积累的大肠杆菌细胞中表达crtG分别导致新月黄质和2，2‘-二羟基-β-胡萝卜素的形成。在此基础上，提出了海藻ATCC 31461合成Nostoxantin的生化途径。
Most Sphingomonas species synthesize the yellow carotenoid nostoxanthin. However, the carotenoid biosynthetic pathway of these species remains unclear. In this study, we cloned and characterized a carotenoid biosynthesis gene cluster containing four carotenogenic genes (crtG, crtY, crtI and crtB) and a β-carotene hydroxylase gene (crtZ) located outside the cluster, from the gellan-gum producing bacterium Sphingomonas elodea ATCC 31461. Each of these genes was inactivated, and the biochemical function of each gene was confirmed based on chromatographic and spectroscopic analysis of the intermediates accumulated in the knockout mutants. Moreover, the crtG gene encoding the 2,2′-β-hydroxylase and the crtZ gene encoding the β-carotene hydroxylase, both responsible for hydroxylation of β-carotene, were confirmed by complementation studies using Escherichia coli producing different carotenoids. Expression of crtG in zeaxanthin and β-carotene accumulating E. coli cells resulted in the formation of nostoxanthin and 2,2′-dihydroxy-β-carotene, respectively. Based on these results, a biochemical pathway for synthesis of nostoxanthin in S. elodea ATCC 31461 is proposed.