MECHANISMS OF ARSENIC TRANSPORT AND BIOTRANSFORMATIONS

项目摘要/摘要：砷是最普遍的毒素，被美国环保局认为是 对人类健康最重大的潜在环境威胁。接触砷是致癌的原因，心脏 疾病，儿童发育迟缓，并扰乱人类微生物群。我们的研究计划 在我们NIGMS赠款的当前资助期内蓬勃发展，专注于砷转运体 和生物转化，这改变了它的可用性、形态、流动性和毒性。我们独一无二 有资格参与这个项目：在这笔赠款的有效期内，我的团队确定并描述了大多数 参与砷运输、生物转化和抗性的ARS基因/蛋白及其对植物生长的影响 全球砷生物循环。我们发现了砷甲基化循环的酶并阐明了 生物转化酶的机理和结构，开发的生物传感器 有机砷类除草剂和发现的具有新型抗菌潜力的有机砷类化合物 探员们。我对未来五年的目标分为四类。1)酶的结构/功能分析 砷的生物转化。我们将阐明ArsM亚砷酸盐S的催化循环- 腺苷甲硫酮(SAM)甲基转移酶、Arsh甲基砷酸氧化酶、Arsi C-As键裂解酶 对精氨酸乙酰转移酶进行生化和结构分析。2)监管和生物传感。 我们将确定金属调控的结构细节。我们将为传感设计新的应用 环境有机砷污染物。3)砷转运蛋白；我们确定了一些新的渗透率 用于有机砷化合物，并将通过结合分子遗传学确定运输机制， 生物化学和结晶学。4)砷类抗生素；我们最近鉴定了两种天然有机砷 具有抗生素活性的产品。我们将确定合成的途径和作用模式 这些新的化合物和发现具有潜在保健应用的新的天然产品。我的整体 视觉是一项具有足够广度的研究计划，它包括识别大脑的生理功能。 已知的抗砷基因和足够的深度来阐明其分子机制。微生物 基因组中有许多与砷相关的未定性基因。有预测的渗透率和酶 没有已知的底物或功能。我们预测这些物质与砷的运输或生物转化有关。 我们将挖掘微生物基因组以寻找新的ars基因，推断它们的进化史，并确定它们是如何 影响环境军火库的循环。我们将发现它们的生理功能。他们的蛋白质 产品将进行提纯，并通过生化和结构分析进行表征。我最重要的主题是 为理解全球砷生物循环及其对地球环境的影响作出重大贡献 人类健康。

Project Summary/Abstract: Arsenic is the most pervasive toxin, considered by the EPA to be one the most significant potential environmental threats to human health. Arsenic exposure is a cause of cancer, heart disease, childhood developmental delay, and disrupts the human microbiome. Our research program blossomed during the current funding period of our NIGMS grant, focusing on arsenic transporters and biotransformations, which modify its availability, speciation, mobility and toxicity. We are uniquely qualified for this project: over the lifetime of this grant, my group identified and characterized the majority of ars genes/proteins involved in arsenic transport, biotransformations and resistance and their impact on the global arsenic biogeocycle. We discovered enzymes of the arsenic methylation cycle and elucidated mechanisms and structures of the enzymes of biotransformation, developed biosensors for organoarsenicals herbicides and discovered organoarsenicals with the potential to be novel antimicrobial agents. My goals for the next five years fall into four categories. 1) Structure/function analysis of enzymes of arsenic biotransformations. We will elucidate the catalytic cycle of the ArsM arsenite S- adenosylmethione (SAM) methyltransferase, the ArsH methylarsenite oxidases, the ArsI C-As bond lyases and the ArsN N-acetyltransferase through biochemical and structural analysis. 2) Regulation and biosensing. We will determine the structural details of metalloregulation. We will devise new applications for sensing environmental organoarsenical pollutants. 3) Arsenic transporters; we identified a number of new permeases for organoarsenicals and will determine the mechanism of transport by a combination of molecular genetics, biochemistry and crystallography. 4) Arsenical antibiotics; we recently identified two organoarsenical natural products with antibiotic activity. We will determine the pathways of synthesis and mode of action of these novel compounds and discover new natural products with potential health applications. My overall vision is a research program of sufficient breadth to encompass identification of the physiological roles of known arsenic resistance genes and sufficient depth to elucidate their molecular mechanisms. Microbial genomes have many uncharacterized arsenic-related genes. There are predicted permeases and enzymes with no known substrate or function. We predict these are involved in arsenical transport or biotransformations. We will mine microbial genomes for new ars genes, deduce their evolutionary histories and determine how they affect cycling of environmental arsenicals. We will discover their physiological functions. Their protein products will be purified and characterized by biochemical and structural analyses. My overarching theme is to make substantial contributions to understanding of the global arsenic biogeocycle and its impact on human health.