Chloroplast Lipid Composition: Connecting Biophysics to Photosynthetic Function

叶绿体脂质成分：将生物物理学与光合功能联系起来

• 批准号: 1555581
• 负责人: John Browse
• 金额: $ 57.54万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2020-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1555581&HistoricalAwards=false
• 关键词: Chloroplast; Lipid; Composition; Connecting; Biophysics

Life on Earth depends on plant photosynthesis, so it is vital that we fully understand all the component systems that contribute to photosynthetic function. Despite considerable research effort over the last twenty years, we still do not know how the lipid composition of the photosynthetic (thylakoid) membrane affects photosynthesis. This project aims to discover the particular lipid requirements for chloroplast biogenesis and function. The project will use the full range of biochemical, molecular and genetic techniques to investigate mutants of the model plant, Arabidopsis, in which different changes in membrane lipid composition are associated with dramatic phenotypes. The knowledge gained will help scientists predict the likely consequences of environmental changes on plant growth and crop productivity. Eventually it will be possible to manipulate membrane lipid composition of plants to better suit particular environmental conditions. Because photosynthesis is central to plant productivity, the extensive temperature-dependent effects observed in the mutants have wide implications for understanding the temperature responses of plants, and agricultural production systems. The project will provide opportunities for graduate and undergraduate students to receive training and experience in plant biology research relevant to agriculture, forestry and other fields of plant production. In particular, the project participants will contribute to an outreach program that uses experiential learning and peer mentoring to encourage Native American high school students to enroll in STEM disciplines in college.This proposal focuses on two new classes of mutants with distinct phenotypes. In the fab1 mutant, an increase in 16:0 results in the collapse of photosynthesis after 2-3 weeks at 2°C, and to destruction of chloroplasts. A collection of suppressor mutations that allow survival of fab1 at 2°C have been isolated. Cloning and characterization of these will provide information about the photosynthetic processes that are most susceptible to the membrane alterations in fab1 plants. The project has generated an allelic series of fad2 fad6 mutants containing 5% to 46% polyunsaturated fatty acids (vs. 77% in wild type) that provide the first opportunity to explore, in detail, the relationship between thylakoid unsaturation and chloroplast function. Analyses indicate that an increase in leakage of protons through the thylakoid membrane is one possible defect in the mutants. The project has also discovered alterations in the capacities of different pathways of thylakoid protein transport in other mutants and these investigations will be extended to include the fad2 fad6 mutants. The results obtained will permit the development and testing of mechanistic models that relate the physiological phenotypes of the mutants to the biophysics of membrane lipid structure. The complementary paths of investigation described in this proposal promise important advances in the application of biophysical principles to understanding how lipid molecules contribute to the functioning of chloroplasts and the responses of plants to environmental change.

地球上的生命依赖于植物的光合作用，因此我们必须充分了解有助于光合作用的所有组成系统。 尽管在过去的二十年里进行了大量的研究，但我们仍然不知道光合作用（类囊体）膜的脂质组成如何影响光合作用。 该项目旨在发现叶绿体生物发生和功能的特殊脂质需求。 该项目将使用全方位的生物化学，分子和遗传技术来研究模式植物拟南芥的突变体，其中膜脂组成的不同变化与显着的表型相关。所获得的知识将有助于科学家预测环境变化对植物生长和作物生产力的可能后果。 最终将有可能操纵植物的膜脂组成，以更好地适应特定的环境条件。 由于光合作用是植物生产力的核心，在突变体中观察到的广泛的温度依赖性效应对理解植物和农业生产系统的温度响应具有广泛的意义。 该项目将为研究生和本科生提供机会，接受与农业、林业和其他植物生产领域有关的植物生物学研究方面的培训和经验。 特别是，项目参与者将为一项外展计划做出贡献，该计划使用体验式学习和同伴指导来鼓励美国原住民高中生在大学中报名STEM学科。该提案重点关注两类具有不同表型的新突变体。在fab 1突变体中，16：0的增加导致在2°C下2-3周后光合作用的崩溃和叶绿体的破坏。已经分离出一系列允许fab 1在2°C下存活的抑制突变。这些基因的克隆和鉴定将为fab 1植物中最易受膜改变影响的光合过程提供信息。该项目已经产生了一个等位基因系列的fad 2 fad 6突变体含有5%至46%的多不饱和脂肪酸（野生型为77%），提供了第一个机会，详细探索类囊体不饱和和叶绿体功能之间的关系。分析表明，通过类囊体膜的质子泄漏的增加是突变体中的一个可能的缺陷。该项目还发现了其他突变体中不同类囊体蛋白转运途径能力的改变，这些研究将扩展到包括fad 2 fad 6突变体。所获得的结果将允许开发和测试的机制模型，相关的生理表型的突变体的膜脂质结构的生物物理学。在这个建议中描述的调查的补充路径承诺的重要进展，在应用生物物理学原理，了解脂质分子如何有助于叶绿体的功能和植物对环境变化的反应。