Elucidating the Function in Iron Homeostasis and Transport of the VTL Family of Vacuolar Membrane Proteins in Arabidopsis

阐明拟南芥液泡膜蛋白 VTL 家族在铁稳态和运输中的功能

• 批准号: 194980302
• 负责人: Professor Dr. Thomas J. Buckhout, Ph.D.
• 金额: --
• 依托单位: Arbeitsgruppe Angewandte Botanik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/194980302?language=en
• 关键词: Elucidating; Function; Iron; Homeostasis; Transport

In the continuation of the project we wish to pursue the investigation of the functions of VTL proteins in iron homeostasis and to establish whether the VTL transporters are suitable tools for increasing the iron storage capacity in plants. The following goals will be pursued. 1. Investigation of the Transport Characteristics of the VTL Proteins and their intracellular localization We have multiple lines of evidence that indicate the presence of the VTL proteins on the vacuolar membrane and that they play an important role in iron homeostasis. Complementation of the ccc1 mutant by heterologous expression of VTL1, 2 or 5 lends further support for their roll in vacuolar transport and homeostasis of iron. It is necessary, however, to demonstrate iron transport directly and to determine the kinetic properties of transport by the VTLs. We propose accomplishing this by iron transport assays using vacuoles isolated from yeast cells that over-express the VTL genes. In parallel to heterologous expression, intracellular localization of the VTL proteins will be investigated. 2. Optimizing Iron Storage in Plants. A goal that is being pursued also by others is to increase the iron storage capacity of plants. Obtaining this goal would produce hardier plants and crops with improved nutritional value for food and fodder. We feel that with the VTL transporters we have additional possibilities for increasing iron in plants. We have published increased iron content in nramp3/nramp4 mutant seeds that over-express VTL1, 2 or 5 (Gollhofer et al., 2014). We have unpublished data showing that VTL2, 4 and 5 over-expression lines, now in the third generation, have from 50 to 100% higher iron in seeds than the Col wild-type. Thus, over-expression of the VTL genes can lead to an increased iron storage capacity. We wish to extend these findings and combine them with unique approaches to increase the iron content of seeds, and thereby develop a model for engineering an increase in plant iron for a wide range of plant species. 3. Screening for Improved Growth on Poorly Available Iron. Beginning in the Fall of 2015 and continuing for one academic year Prof. Wolfgang Schmidt will be on sabbatical leave from the Academia Sinica at the Institute of Biology, Humboldt-Universität zu Berlin. In my laboratory we will conduct a screening of Arabidopsis ecotypes for their ability to grow on poorly available iron sources (e.g. FeCl3 at pH 7.0). Recently, the spectrum of iron mobilization strategies has been expanded to include synthesis and secretion of phenolic compounds in Arabidopsis (Rodríguez-Celm et al., 2013; Schmid et al., 2014). This phenolic based uptake strategy is likely important for iron uptake in neutral and alkaline soils, and it may be the mechanism behind resistance to lime-/bicarbonate-induced chlorosis in crop plants. Our goal is to identify new players that permit plant growth on poorly available iron soils.

在该项目的继续中，我们希望继续研究铁蛋白在铁稳态中的功能，并确定铁转运蛋白是否是增加植物铁储存能力的合适工具。将努力实现以下目标。1.铁蛋白的转运特性及其细胞内定位的研究我们有多条证据表明液泡膜上存在铁蛋白，并且它们在铁稳态中起重要作用。通过VTL 1、2或5的异源表达对ccc 1突变体的互补进一步支持了它们在铁的液泡运输和体内平衡中的作用。然而，有必要直接证明铁的运输，并确定运输的动力学特性的VTL。我们建议通过铁转运试验，使用空泡分离的酵母细胞，过表达的hepatocyte基因。在异源表达的同时，将研究cDNA 3蛋白的细胞内定位。2.优化植物中的铁储存。其他人也在追求的一个目标是增加植物的铁储存能力。实现这一目标将使植物和作物更耐寒，并提高其作为食物和饲料的营养价值。我们认为，有了铁转运蛋白，我们就有了增加植物中铁含量的额外可能性。我们已经公开了在过表达VTL 1、2或5的nramp 3/nramp 4突变种子中增加的铁含量（Gollhofer等人，2014年）。我们有未发表的数据显示，VTL 2、4和5过表达株系，现在是第三代，在种子中的铁比Col野生型高50%至100%。因此，过表达的铁蛋白基因可以导致增加的铁储存能力。我们希望扩展这些发现，并将它们与增加种子铁含量的独特方法联合收割机相结合，从而开发一种用于工程化增加植物铁的模型。3.筛选改善生长的低可用铁。从2015年秋季开始，Wolfgang施密特教授将在中央研究院柏林洪堡大学生物研究所休假一学年。在我的实验室中，我们将对拟南芥生态型进行筛选，以确定它们在难以获得的铁源（例如pH 7.0的FeCl 3）上生长的能力。最近，铁动员策略的范围已经扩展到包括拟南芥中酚类化合物的合成和分泌（Rodríguez-Celm et al.，2013年; Schmid等人，2014年）。这种基于酚类的吸收策略对于中性和碱性土壤中的铁吸收可能是重要的，并且它可能是作物植物对石灰/碳酸氢盐诱导的黄化的抗性背后的机制。我们的目标是确定新的球员，允许植物生长在缺铁土壤。