Metal Homeostasis and Tolerance in Plant Chloroplasts - The Role of PAA1 and AtCUTA

植物叶绿体中的金属稳态和耐受性 - PAA1 和 AtCUTA 的作用

• 批准号: 0091163
• 负责人: Marinus Pilon
• 金额: $ 33万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0091163&HistoricalAwards=false
• 关键词: Metal; Homeostasis; Tolerance; Plant; Chloroplasts

All organisms must regulate metal homeostasis, which involves metaluptake, transport, storage, and distribution. The goal of this research isto gain insight into the basic mechanisms by which heavy metal homeostasisis regulated in plants, particularly in the chloroplast. The chloroplast isthe location of photosynthesis, the process that drives all life on earth.This complex process involves a set of enzymes and pigments, many of whichrequire specific heavy metal ions as cofactors, e.g. copper, iron,magnesium, manganese, and zinc. Although these metals are necessarycomponents of the photosynthetic machinery - as well as of other enzymes inthe cell - they are toxic when present in excess. Therefore,chloroplast copper homeostasis is vital for plant heath and productivity.This project focuses on two Arabidopsis thaliana genes, PAA1 and AtCUTA,both thought to be involved in metal homeostasis. Judged from the presenceof putative chloroplast import sequences, both gene products are predictedto be functional in the chloroplast. Based on similarities with genescloned from other sources, Paa1 protein is likely involved in coppertransport, and AtCutA protein in the regulation of copper tolerance. Thesehypotheses regarding the location and functions of these proteins areanalyzed in this project. The mRNA levels of both genes will beanalyzed with respect to tissue distribution, developmental stage, andenvironmental conditions such as metal toxicity or metal deficiency. Theintracellular location of the proteins encoded by the genes will bedetermined. To investigate the functions of the genes in vivo, Dr.Pilon will analyze plant linesthat have T-DNA insertions and plant lines that overexpress the genes. They will be studied with respect to metal homeostasis and assembly of the photosynthetic apparatus. Finally, the metal binding properties and metal specificity of the encoded proteins will be determined. The results from this project will provide much-needed fundamental knowledge aboutheavy metal homeostasis mechanisms in chloroplasts, a largely unexplored field of research. In addition, this work may lead to the development of strategies to manipulate metal tolerance and accumulation inplants. This, in turn, may be used to increase crop yields and nutritionalvalue of plants, or to help clean up metal-contaminated sites.

所有生物体都必须调节金属稳态，这涉及金属的吸收、运输、储存和分配。这项研究的目的是深入了解植物（特别是叶绿体）重金属稳态调节的基本机制。叶绿体是光合作用的所在地，光合作用是驱动地球上所有生命的过程。这个复杂的过程涉及一组酶和色素，其中许多需要特定的重金属离子作为辅助因子，例如铜、铁、镁、锰和锌。尽管这些金属是光合作用机器以及细胞中其他酶的必要组成部分，但它们过量存在时会产生毒性。因此，叶绿体铜稳态对于植物健康和生产力至关重要。该项目重点关注拟南芥的两个基因PAA1和AtCUTA，这两个基因被认为与金属稳态有关。根据推定的叶绿体输入序列的存在来判断，这两种基因产物预计在叶绿体中具有功能。基于与其他来源克隆的基因的相似性，Paa1 蛋白可能参与铜转运，而 AtCutA 蛋白可能参与铜耐受性的调节。本项目分析了有关这些蛋白质的位置和功能的这些假设。将根据组织分布、发育阶段和环境条件（例如金属毒性或金属缺乏）来分析这两个基因的 mRNA 水平。将确定基因编码的蛋白质的细胞内位置。为了研究基因在体内的功能，Pilon 博士将分析具有 T-DNA 插入的植物系和过度表达该基因的植物系。 他们将在金属稳态和光合装置的组装方面进行研究。最后，将确定所编码蛋白质的金属结合特性和金属特异性。 该项目的结果将提供急需的关于叶绿体中重金属稳态机制的基础知识，这是一个很大程度上尚未探索的研究领域。 此外，这项工作可能会导致控制植物体内金属耐受性和积累的策略的发展。反过来，这可以用来提高作物产量和植物的营养价值，或帮助清理金属污染场地。