MECHANISMS OF ARSENIC TRANSPORT AND BIOTRANSFORMATIONS

项目概要/摘要：砷是最普遍的毒素，被EPA认为是最常见的有毒物质之一。 对人类健康最大的潜在环境威胁。砷暴露是癌症的一个原因，心脏 疾病，儿童发育迟缓，并破坏人类微生物组。我们的研究项目 在我们的NIGMS赠款的当前资助期间， 和生物转化，改变其可用性，物种形成，流动性和毒性。我们是唯一 有资格参加这个项目：在这个赠款的生命周期中，我的小组确定并描述了大多数 参与砷转运、生物转化和抗性的ars基因/蛋白及其对砷代谢的影响 全球砷循环我们发现了砷甲基化循环的酶， 生物转化酶的结构和机制，开发的生物传感器 有机砷除草剂和发现的具有新型抗菌潜力的有机砷 剂.我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甲基亚砷酸氧化酶、ArsI C-As键裂合酶 和ArsN N-乙酰基转移酶进行了生化和结构分析。2)调节和生物传感。 我们将确定金属调节的结构细节。我们将设计新的传感应用 环境有机砷污染物。3)砷转运蛋白;我们发现了一些新的渗透酶 并将通过分子遗传学的组合来确定运输机制， 生物化学和晶体学。4)含砷抗生素;我们最近发现了两种有机砷天然 具有抗菌活性的产品。我们将确定的合成途径和行动模式的 这些新的化合物，并发现新的天然产品与潜在的健康应用。我的整体 视觉是一个足够广泛的研究计划，包括识别的生理作用， 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有关的基因。有预测的渗透酶和酶 没有已知的底物或功能。我们预测这些参与砷的运输或生物转化。 我们将从微生物基因组中挖掘新的ars基因，推断它们的进化历史，并确定它们是如何进化的。 影响环境砷的循环。我们将发现它们的生理功能。它们的蛋白质 产物将被纯化并通过生物化学和结构分析表征。我的首要主题是 为了解全球砷循环及其对环境的影响做出实质性贡献。 人体健康

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.