Phytochelatin synthase & resistance to heavy metals

植物螯合素合酶

• 批准号: 6577797
• 负责人: JULIAN I SCHROEDER
• 金额: $ 17.5万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6577797
• 关键词: Cruciferae; arsenic; biological signal transduction; biotransformation; cadmium; environmental health; environmental toxicology; environmental transport; enzyme activity; gene expression; genetically modified plants; hazardous substances; heavy metals; lead; mercury; plant physiology; soil pollution; waste treatment; water pollution

Soils and waters with high levels of toxic metals such as cadmium (Cd), arsenic (As), lead (Pb) and mercury (Hg) are detrimental to human and environmental health. These four metals are among the Superfund;'s top five priority hazardous substances. Studies suggest that uptake of heavy metals into plant via the root system could provide a potent and cost effective approach for toxic metal removal and remediation of soils and waters. In plants and fungi, phytochelatins are major heavy metal chelating and detoxifying thiolate peptides, that form complexes with and detoxify heavy metals, including Cd, Zn, Pb, Hg and based on recent research also As. The enzyme phytochelatin synthase (PCS) produces phytochelatin, thus functioning as a major catalytic metal detoxification mechanisms in plants. However genes encoding phytochelatin synthases, had not yet been identified. We have recently cloned a new gene family (PCS) encoding phytochelatin synthases in plants and fungi. Expression of PCS cDNAs in S. cerevisiae dramatically enhance resistance to cadmium. Disruption of the PCS genes in S. pombe and Arabidopsis thaliana produces increased heavy metal sensitivity. Recombinant PCS proteins synthesize phytochelatins in vitro. We will test the hypotheses that stress-signaling pathways contribute to PCS induction and detoxification and that transgenic expression of PCS genes can, together with other metal-interacting mechanisms, enhance heavy metal hyper-accumulation and removal by plants. To test these hypotheses we will: (I) Characterize signaling mechanisms that induce PCS expression. (II) Characterize PCS expression and localization in Brassica juncea, which is one of the major plant species being studied for heavy metal biomediation. (III) Pursue transgenic over-expression in plants of PCS together with associated metal detoxification mechanisms to test for enhanced heavy metal tolerance and accumulation and (IV) provide selected transgenic lines to Phytotech Inc to include in field trials on super fund sites. (V) Pursue novel genetic activation-tagging screens in Arabidopsis and Cd-induced microarray analyses to identify new genes and pathways involved in heavy metal accumulation in plants. Results from these studies could play a central role in the development of future phytoremediation strategies for heavy metal uptake and biological removal of heavy metals form contaminated soils and waters.

具有高水平有毒金属的土壤和水，例如镉（CD），砷（AS），铅（PB）和汞（HG）对人类和环境健康有害。这四种金属是超级基金之一；排名前五的危险物质。研究表明，通过根系，将重金属吸收到植物中可以为有毒金属去除和补救土壤和水提供一种有效且具有成本效益的方法。在植物和真菌中，植物chelatins是主要的重金属螯合和排毒硫代肽，它们与CD，Zn，Pb，HG在内的重金属形成并为包括CD，Zn，Pb，HG的重金属排毒，并且基于最近的研究。酶植物切氯酸酶合酶（PC）产生植物切切素，因此充当植物中主要的催化金属排毒机制。然而，尚未鉴定编码植物切切尔蛋白合酶的基因。我们最近克隆了一个新的基因家族（PC），该基因家族编码植物和真菌中的植物毒素合酶。酿酒酵母中PCS cDNA的表达显着增强了对镉的耐药性。 pombe和拟南芥中PCS基因的破坏会产生重金属灵敏度的提高。重组PCS蛋白质在体外合成植物chelatins。我们将测试应力信号途径有助于PC诱导和排毒的假设，并且PCS基因的转基因表达与其他金属相互作用机制可以增强重金属的高金属高蓄能和植物的去除。为了检验这些假设，我们将：（i）表征诱导PC表达的信号传导机制。 （ii）表征PCS表达和植树中的定位，这是正在研究重金属生物化的主要植物物种之一。 （iii）在PC的植物中追求转基因过表达，以及相关的金属排毒机制，以测试增强的重金属耐受性和积累，（iv）为Phytotech Inc提供选定的转基因线，以包括在超级基金地点的实地试验中。 （v）在拟南芥和CD诱导的微阵列分析中追求新的遗传激活筛选，以鉴定植物中重金属积累涉及的新基因和途径。这些研究的结果可能在未来的植物修复策略的发展中起着核心作用，用于重金属摄取和重金属的生物学去除形成被污染的土壤和水。