Beyond static metabolic maps - Understanding the cellular organization and dynamics of lipid flux for enhanced seed oil production

植物油是一种有价值的可再生资源，可用于食品，燃料和化学品（塑料，油漆，化妆品等）的减少碳（脂肪酸）。为了满足日益增长的人口对植物油的日益增长的需求，将需要增加的油产量和优化用于社会应用的植物油脂肪酸组合物。目前的知识表明，植物油的生物合成与细胞功能所需的基本膜脂质的产生重叠。这项研究阐明了植物如何平衡油的积累与膜脂的合成，使作物育种和植物生物工程的努力可以优化植物油的生产，而不影响生物膜的性能。该项目使用遗传突变体，过表达线，蛋白质定位和动态相互作用，体内同位素标记，以及非稳态通量的数学建模，以产生脂质代谢网络功能和动力学的定量描述。基于项目结果的新工程策略可能提供具有营养价值的食用油或化学反应性脂质的替代来源，这些脂质可以在化学合成中功能性地取代石油。项目成果还可能导致开发新的增值作物，从而振兴低收入农村农业社区。该项目与华盛顿州立大学的探索学院新兴领导者（EXCEL）项目合作，旨在增加美国原住民社区对STEM科目的参与。三名博士后科学家，一名博士后研究员和多名本科生正在接受科学研究和推广培训，成为下一代科学领导者，他们将面对未来的科学挑战，提高农业产量，为社会造福。有价值的植物油和必需的膜脂通过重叠的代谢网络组装。通过网络的脂肪酸流量的路径最终决定了最终的油脂肪酸组成，但植物如何控制脂肪酸流量通过这个网络的脂质组装是未知的。一个重要的特别未知的是植物如何控制膜和油的生物合成之间的关键中间体（甘油二酯）的使用。这项研究利用多学科团队的专业知识来阐明脂质代谢网络结构、通量和亚细胞空间组织。遗传突变体，过表达线，蛋白质定位和动态相互作用，在体内同位素标记，和数学建模的组合被用来开发脂质代谢网络功能和动力学的定量描述。这一定量图像包括细胞组织和脂肪酸通量的酶控制，通过影响种子油积累和组成的脂质代谢网络的不同分支。所获得的知识将导致范式转变，超越以前用于开发生物工程策略的静态代谢物的当前网络描述。基于体内同位素标记的代谢通量图增强了对脂质网络功能的定量和动态理解，并能够改进工程工作。该项目还提供了重要的新工具，以帮助指导更好的代谢工程（或有针对性的育种）策略的设计，以满足未来的植物油需求。该奖项反映了NSF的法定使命，并已被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Plant oils are a valuable renewable resource of reduced carbon (fatty acids) used for food, fuels, and chemicals (plastics, paints, cosmetics, etc.). To meet the rising demand of an increasing human population for plant oils will require increased oil production and optimization of plant oil fatty acid compositions for societal applications. Current knowledge indicates that plant oil biosynthesis overlaps with essential membrane lipid production required for cellular function. This research is elucidating how plants balance accumulation of oil with synthesis of membrane lipids so that crop breeding and plant bioengineering efforts can optimize plant oil production without affecting the properties of biological membranes. The project uses genetic mutants, overexpression lines, protein localization and dynamic interactions, in vivo isotopic labeling, and mathematical modeling of non-stationary flux to produce a quantitative description of lipid metabolic network function and dynamics. New engineering strategies based on project results may provide alternative sources of nutritionally valuable food oils, or chemically reactive lipids that can functionally replace petroleum in chemical syntheses. Project results could also lead to the development of new value-added crops that can reinvigorate low-income rural farming communities. This project collaborates with the EXploring College Emerging Leaders (EXCEL) program at Washington State University that seeks to increase participation of Native American communities in STEM subjects. The three postdoctoral scientists, one post bachelor researcher, and multiple undergraduate students are being trained in scientific research and outreach to become the next generation of scientific leaders who will face future scientific challenges and enhance agricultural output for societal gain. Valuable plant oils and essential membrane lipids are assembled by an overlapping metabolic network. The path of fatty acid flux through the network ultimately determines the final oil fatty acid composition, yet how plants control fatty acid flux through this network of lipid assembly is unknown. An important particular unknown is how plants control the use of key intermediates (diacylglycerol) between membrane and oil biosynthesis. This research leverages the expertise of a multi-disciplinary team to elucidate lipid metabolic network structure, fluxes, and sub-cellular spatial organization. A combination of genetic mutants, over-expression lines, protein localization and dynamic interactions, in vivo isotopic labeling, and mathematical modeling is used to develop a quantitative description of lipid metabolic network function and dynamics. This quantitative picture includes the cellular organization and the enzymatic control of fatty acid flux through different branches of the lipid metabolic network that affect seed oil accumulation and composition. The knowledge gained will result in a paradigm shift beyond the current network descriptions of static metabolites that have previously been used to develop bioengineering strategies. In vivo isotopic labeling-based metabolic flux maps enhance the quantitative and dynamic understanding of lipid network function and enable improved engineering efforts. The project also provides important new tools to help guide the design of better metabolic engineering (or targeted breeding) strategies to meet the plant oil needs of the future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.