Functional and evolutionary analysis of chloroplast metabolite transporters in the C4 plant maize

由于生物化学无机碳富集机制，在光合作用成为二氧化碳限制的条件下，如高温、干旱、盐碱化条件下，c4 -光合作用优于c3 -光合作用。已经确定了C4无机碳泵的酶促步骤，并对酶和基因及其调控进行了详细的表征。然而，大多数参与这个生化无机碳泵的代谢物转运体，特别是叶绿体包膜的转运体，是未知的。本奖项要验证的假设是，参与C4-光合途径的质体包膜转运蛋白可以根据其在C4叶绿体包膜中的丰度及其时间、发育和空间表达模式来识别。研究者建议使用比较和定量的蛋白质组学和转录谱分析来鉴定这些转运蛋白的候选基因，并将纯化的重组转运蛋白重组成脂质体，以对相应蛋白进行功能表征。这些研究有望显著增加对C4光合作用基本生理过程的认识。该项目将深入了解质体包膜中运输蛋白如何连接和协调复杂的生化途径。拟议活动产生的更广泛影响本科生和研究生将参与该项目。他们将接受跨学科的培训，这样他们就可以超越自己的专业领域，对植物生物学有一个综合的看法。研究活动将通过培训处理膜转运体的初级科学家纳入教学，这是该机构目前没有代表的领域。招收植物膜运输领域的研究生和高级研究人员参与本科教学。本项目产生的植物材料将用于向K-12教师介绍植物基因工程，并在夏季课程中对K-12教师进行现代分子技术培训。一个公共项目数据库将为植物研究界提供有关玉米叶绿体包膜蛋白质组的信息。

Due to a biochemical inorganic carbon-concentrating mechanism, C4-photosynthesis is advantageous to C3-photosynthesis under conditions where photosynthesis becomes carbon dioxide-limited, such as high temperature, drought, and saline conditions. The enzymatic steps involved in the C4 inorganic carbon pump have been identified, and the enzymes and genes and their regulation have been characterized in great detail. However, most of the metabolite transporters involved in this biochemical inorganic carbon pump, in particular those of the chloroplast envelope membrane, are unknown. The hypothesis to be tested in this award is that plastid envelope membrane transporters involved in the C4-photosynthetic pathway can be identified based on their abundance in C4 chloroplast envelope membranes and their temporal, developmental, and spatial expression pattern. The investigator proposes to use comparative and quantitative proteomics and transcript profiling to identify candidate genes for these transporters, and reconstitution of purified recombinant transporter proteins into liposomes to functionally characterize the corresponding proteins.These studies are expected to significantly increase understanding of the fundamental physiological process of C4 photosynthesis. The project will lead to in-depth understanding of how a complex biochemical pathway is connected and coordinated by transport proteins in the plastid envelope membrane.Broader impacts resulting from the proposed activityUndergraduate and graduate students will participate in the project. They will receive cross disciplinary training so they can think beyond their individual field of expertise towards an integrative view of plant biology. Research activities will be integrated into teaching by training junior scientists in the handling of membrane transporters, a field currently not represented at this institution. Graduate students and senior researchers will be involved in undergraduate teaching in the field of plant membrane transport. Plant material generated in this project will be used to introduce K-12 teachers into genetic engineering of plants and to train K-12 teachers in modern molecular techniques in summer courses. A public project database will provide the plant research community with information on maize chloroplast envelope membrane proteome.