环境胁迫条件下杜氏藻类胡萝卜素合成关键酶基因的代谢调控机制

Dunaliella is the most salt-tolerant eukaryotes with the highest β-carotene content. Applicant of this project takes the lead in reseach on the secondary metabolism pathway of carotenoids in Dunaliella, and has made great progresses. Applicant has obtained a series of results with the original meaning in, but not limited to, the following areas: the cloning of the key enzyme genes in β-carotene pathway and their promoters' sequence and functional analysis including the verification of salt and light motifs; the construction of the extraneous high-level expressed systems for the secondary metabolic pathway of carotenoid in Dunaliella; in vivo elucidation for the catalytic efficacy and efficiency of lycopene β-cyclase from Dunaliella and its metabolic construction for a genetically engineered bacteria; adaptation mechanism of Dunaliella to salt stresses, etc. The metabolic mechanism of carotenoids in Dunaliella needs to be further explanied at the level of molecular regulation. Dunaliella is characterized by its high level accumulation of natural β-carotene under various stress conditions, based on which the project aims to study its molecular mechanisms regulated by extreme environments, such as the high-salinity, high light intensity, and nutrient limitation, on the secondary metabolism of carotenoids in Dunaliella. The project is designed to reveal the issues of regulation and feedback regulation between two closely related pathways of methylerythritol phosphate (MEP) and carotenoids metabolism through the research on the responses of key enzyme genes and their promoters in Dunaliella to the environmental factors, to reveal the principle that the pathway of carotenoids of Dunaliella competes the C40 flow from the MEP pathway. Thus, to calrify the molecular mechanisms that Dunaliella accumulates a high degree of β-carotene. The project is of advance and innovation at the international level, and will enrich and develop the theory of secondary metabolism of carotenoids.

杜氏藻是β-胡萝卜素含量最高、最耐盐的真核生物。申请人在杜氏藻类胡萝卜素代谢领域进行了长期系统研究，在β-胡萝卜素代谢途径关键酶基因的克隆及其启动子盐和光作用元件分析与验证、类胡萝卜素代谢途径外源表达系统的构建、番茄红素β-环化酶催化高效性，以及杜氏藻盐胁迫响应机制等方面取得了一系列具有原创意义的成果。杜氏藻类胡萝卜素代谢机理需要进一步从生化调控上加以阐释。本项目围绕杜氏藻在胁迫条件下高度累积β-胡萝卜素这一突出特性，以研究高盐度、高光强、营养限制等极端环境对杜氏藻类胡萝卜素次生代谢调控的分子机制为核心，针对MEP与类胡萝卜素这两个紧密相关的代谢路径间的调控与反馈调控问题，通过关键酶基因对环境因子的应答研究，揭示杜氏藻类胡萝卜素途径从MEP途径竞争性获得合成前体物的作用原理，阐明杜氏藻高度累积β-胡萝卜素的分子机制。项目在国际层面具有先进性和创新性，将丰富和发展类胡萝卜素次生代谢的理论。

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