Characterization of Calcium Binding Proteins Involved in Calcium Regulation in Plants

参与植物钙调节的钙结合蛋白的表征

• 批准号: 9305941
• 负责人: Vincent Franceschi
• 金额: --
• 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: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1997-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9305941&HistoricalAwards=false
• 关键词: Characterization; Calcium; Binding; Proteins; Involved

9305941 Franceschi In plants, calcium is taken up and transported along with water. The amount taken up in many plants is directly proportional to the amount of calcium in the soil solution. The water evaporates from the surfaces of the plant and, over time, large amounts of calcium can accumulate in various organs, which necessitates high capacity calcium sequestration systems in the organs of such plants. It is hypothesized that calcium oxalate formation has evolved as a mechanism in plants for removing calcium when it is present at levels that can no longer be controlled by the lower-capacity mechanisms common to all cells. The observations that most plant families produce calcium oxalate, that this product can account for up to 85% of the dry weight of some plant species, and that 90% of the calcium in plants can be in this form, support this hypothesis. Calcium binding proteins have been identified that are specific to those cells (crystal idioblasts) that produce calcium oxalate. One protein is cytosolic and shows antigenic similarity to animal calsequestrin. It is hypothesized that this protein is responsible for buffering the activity of the large fluxes of calcium which must be passing through the cytoplasmic compartment during the rapid process of crystal formation. Three other proteins have been found to be associated with the calcium oxalate crystal matrix, and antibodies have been raised to these proteins. These matrix proteins are thought to be responsible for regulating nucleation and/or growth of the crystals. The next general goal of this research is to characterize the structure and function of these unique proteins to further understand how they function in calcium regulation in plants. Specific objectives are to: (1) Characterize of the molecular properties of the matrix proteins by obtaining and analyzing cDNAs for these proteins. (2) Determine the chemical properties of the matrix proteins. The effects of purified matrix proteins on crystal nucleation and growth will be studied in vitro. (3) Resolve the molecular relationship of matrix proteins and crystal matrix. Immunocytochemical techniques will be used to determine the pattern of protein intercalation in the crystal matrix. (4) Characterize the calsequestrin-like protein. Using antibody and cDNA probes to animal calsequestrin, a cDNA will be isolated from a library constructed from Pistia stratiotes. The cDNA will be sequenced and characterized. (5) Determine the subcellular location of the calsequestrin-like protein by immunocytochemistry. %%% Calcium is involved in the control of many physiological processes in plants, but excess calcium can be harmful. Thus, regulation of calcium is critical to normal plant growth, development and productivity. Previous results from this laboratory suggest that formation of calcium oxalate crystals is a mechanism used by plants to sequester excess calcium. This research will examine the mechanisms by which plants form calcium oxalate crystals. The results will contribute to our understanding of how plants regulate their internal calcium levels. ***

9305941在植物中，钙被吸收并随水沿着运输。许多植物吸收的钙量与土壤溶液中的钙量成正比。水从植物的表面蒸发，并且随着时间的推移，大量的钙可以积聚在各种器官中，这需要在这种植物的器官中的高容量钙螯合系统。据推测，草酸钙的形成已经演变为植物中的一种机制，用于去除钙，当它存在的水平，可以不再由所有细胞共同的低容量机制控制。大多数植物科产生草酸钙，这种产物可以占某些植物物种干重的85%，植物中90%的钙可以以这种形式存在，这一观察结果支持了这一假设。已经鉴定出对产生草酸钙的细胞（晶体异细胞）具有特异性的钙结合蛋白。一种蛋白质是胞质的，并且显示出与动物钙螯合蛋白的抗原相似性。据推测，这种蛋白质负责缓冲在晶体形成的快速过程中必须通过细胞质区室的大量钙通量的活性。已经发现另外三种蛋白质与草酸钙晶体基质相关，并且已经产生了针对这些蛋白质的抗体。这些基质蛋白被认为负责调节晶体的成核和/或生长。本研究的下一个总体目标是表征这些独特蛋白质的结构和功能，以进一步了解它们在植物钙调节中的功能。具体目标是：（1）通过获得和分析这些蛋白质的cDNA来表征基质蛋白质的分子特性。(2)确定基质蛋白的化学性质。将在体外研究纯化的基质蛋白对晶体成核和生长的影响。(3)解析基质蛋白与晶体基质的分子关系。免疫细胞化学技术将用于确定蛋白质嵌入晶体基质的模式。(4)鉴定钙螯合蛋白样蛋白。使用动物钙螯合蛋白的抗体和cDNA探针，将从从水浮莲构建的文库中分离cDNA。将对cDNA进行测序和表征。(5)免疫细胞化学法确定钙螯合蛋白样蛋白的亚细胞定位。钙参与控制植物的许多生理过程，但过量的钙可能是有害的。因此，钙的调节对正常植物生长、发育和生产力至关重要。这个实验室以前的结果表明，草酸钙晶体的形成是植物用来隔离多余钙的一种机制。这项研究将研究植物形成草酸钙晶体的机制。这些结果将有助于我们了解植物如何调节其内部的钙水平。***