Study of an Enzyme that Regulates Oil Synthesis in Seeds

调节种子油合成酶的研究

• 批准号: 9219323
• 负责人: Anthony Huang
• 金额: $ 22.5万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-04-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9219323&HistoricalAwards=false
• 关键词: Study; Enzyme; Regulates; Oil; Synthesis

Synthesis and degradation of triacylglycerols (TAG) in seeds during maturation and germination involve active metabolic pathways. Understanding the detailed mechanism of TAG metabolism will enable the control of food reserve deposition and utilization during active stages of the plant life cycle. It will also provide an indispensable information of how to breed or genetically engineer better seed oils for human utilization. The long term objective of the laboratory is to elucidate the mechanism of TAG metabolism in seeds. The focus is on a crucial TAG synthesizing enzyme, lysophosphatidate (LPA) acyltransferase, in maturing seed. This enzyme catalyzes the incorporation of acyl moiety from acyl CoA to the sn-2 position of 1-acyl-glycerol-3-phosphate, and the product phosphatidate will be further metabolized to either TAG or phospholipids. The enzyme has a very stringent acyl preference on both substrates, and thus controls the incorporation of preferred fatty acids into the sn-1 and sn-2 positions of TAG. The fatty acid composition, and thus the properties of seed TAG, rely heavily on the acyl preference of LPA acyltransferase. In this research proposal, the following two objectives will be pursued. The first objective is to examine whether seed LPA acyltransferase of a special acyl preference from one plant species will be active in another plant species after genetic transformation. Experiments will be performed to characterized seed LPA acyltransferases from palm, Brassica, and meadowfoam, to obtain their genes for transformation of appropriate plants, and to detect activities of the foreign enzymes in the transformed plants. Several different approaches will be used to obtain the gene; these approaches include: screening cDNA libraries for the genes by oligonucleotides deduced from the purified enzyme and by a bacterial gene, and functional complementation with a bacterial mutant. Putative E. coli mutant lines functionally complemented with plant cDNA encoding the enzyme have been obtained; these lines will be studied most intensively. If time permits, we will use the palm and meadowfoam LPA acyltransferase genes to transform Brassica, and analyze the transformed plants for activities of the foreign enzyme. The information will be crucial to our understanding of the control mechanism of fatty acid assembly into TAG in seeds as well as glycerolipids in non seed organs. The second objective is to test if a membrane-associated, lipid-metabolizing enzyme of bacterial origin can be active, in higher plants. by transforming Brassica with an E. coli gene encoding LPA acyltransferase and studying the expression of the bacterial gene in the transformed Brassica. %%% This project aims to take a gene which makes an enzyme that Produces a certain plant oil found in palms, and introduce the gene into other plants to see if they also would produce the palm oil. If this is successful the investigators have found a way for oil produced in plants not common to the US to be available in other species of plants common in this country. Furthermore, these enzymes could be used to make novel lipid biomaterials.

种子中三酰甘油（TAG）的合成与降解 成熟和萌发涉及活跃的代谢途径。 了解TAG代谢的详细机制将使 控制粮食储备的沉积和利用 植物生命周期的活跃阶段。 它还将提供一个 如何繁殖或基因工程的不可或缺的信息 更好的种子油供人类使用。 长期 本实验室的目的是阐明TAG的机制 种子的新陈代谢 重点是关键的TAG合成 酶，溶血磷脂酸（LPA）酰基转移酶，在成熟的种子。 这种酶催化酰基部分从酰基 CoA至1-酰基-甘油-3-磷酸的sn-2位，以及CoA至1-酰基-甘油-3-磷酸的sn-2位。 产物磷脂酸盐将进一步代谢成TAG或 磷脂 这种酶对乙酰基有非常严格的偏好， 这两种基质，并因此控制优选的 脂肪酸进入TAG的sn-1和sn-2位。 脂肪 酸组成，因此种子TAG的性质，严重依赖于 对LPA酰基转移酶的酰基偏好性的影响。 本研究 根据这项建议，将追求以下两个目标。 第一 目的是检查是否种子LPA酰基转移酶的一个 来自一种植物物种特殊酰基偏好将在 另一种植物经过基因转化。 实验 将进行表征种子LPA酰基转移酶， 棕榈，芸苔属，和meadowfoam，以获得他们的基因， 转化适当的植物，并检测 转化植物中的外源酶。 几种不同 方法将用于获得基因;这些方法 包括：用寡核苷酸筛选cDNA文库中的基因 由纯化的酶和细菌基因推导，和 与细菌突变体的功能互补。 推测的E. 与植物cDNA功能互补的大肠杆菌突变株系 已经获得了编码该酶的细胞系;这些细胞系将被研究 最密集。 如果时间允许，我们将使用棕榈树， - 将白花菜LPA酰基转移酶基因转化芸苔属，和 分析转化的植物的外国活动 酵素 这些信息对我们了解 种子中脂肪酸组装成TAG的控制机制， 以及非种子器官中的甘油脂。第二个目标是 来测试是否有一种膜相关的脂质代谢酶 在高等植物中，细菌起源可以是活跃的。 通过变换 Brassica with an E.编码LPA酰基转移酶的大肠杆菌基因， 研究细菌基因在转化的 芸苔 %%% 这个项目的目的是获取一种基因， 产生一种在棕榈树中发现的植物油， 看看它们是否也能生产棕榈油。 如果这是成功的，调查人员已经找到了一种方法， 在美国不常见的工厂生产，在其他国家也有 这个国家常见的植物种类。 而且这些 酶可用于制备新型脂质生物材料。