Bacterial multi-resistance mechanisms: Functional studies on a multi-ligand transporter

我的研究项目植根于了解细菌的毒素抗性机制。我的小组提出了这样一个问题：“什么样的生物化学和生理学使细菌能够对付各种杀菌剂，而不是一种特定的化合物？”我们一直在研究对金属离子，各种有机污染物和工业杀菌剂的抗性。与过去的研究保持一致，我们将继续研究所谓的“多药”耐药转运体，重点关注通常被归类为防腐剂的化合物。防腐剂用于各种领域，包括：化妆品，清洁剂，洗手液，水处理和石油和天然气管道的腐蚀控制。我们将继续关注的多配体转运体是细菌小的多药耐药（SMR）家族蛋白，它将季阳离子化合物（QCC）泵出细胞。研究多配体抗性系统的一个吸引人的地方是底物配体识别存在混杂性，但配体选择仍然具有特异性。SMR蛋白运输的化合物似乎种类繁多，几乎没有化学共性，但它们仍然表现出惊人的选择性；这是如何做到的呢？我们研究的主要SMR蛋白是EmrE （Escherichia coli multi-resistance protein E）。这笔拨款旨在继续我们对SMR蛋白家族的研究。在这个资助周期中，具体目标是：i)确定EmrE的配体结合位点。ii)鉴定参与将毒素完全移出细胞的完整运输系统的其他蛋白质。iii)开始定义EmrE天然底物运输的一些生物化学过程。iv)研究配体对SMR蛋白多聚态和折叠的影响。v)评价细菌对QCC化合物的生理反应。***这些研究的长期目标是提供SMR蛋白的折叠、寡聚、稳定性、配体特异性、功能、生化机制和生理学的生物化学和生物物理图谱，从而有助于理解整体膜蛋白的多重耐药机制和功能。了解细菌对多种化合物的耐药性是开发提高抗菌化合物和新型抗菌药物疗效的关键。这种需求反映在质量保证中心的使用上。到2018年，全球工业和机构清洁产品市场将超过500亿美元，杀菌剂和消毒剂也占全球水处理剂市场的10%以上

My research program is rooted in understanding toxin resistance mechanisms in bacteria. My group asks the question: "what biochemistry and physiology allows bacteria to deal with a variety of biocide agents rather than a specific compound?" We have been studying the resistance to metal ions, various organic pollutants, and industrial biocides. In keeping with past research, we will continue to study the so-called `multi-drug' resistance transporters, focusing on compounds that would be generally classified as antiseptics. Antiseptics are used in a variety of areas including: cosmetics, cleaning agents, hand sanitizers, water treatment and corrosion control in oil and gas pipelines. The group of multi-ligand transporters that we will continue to concentrate on is the bacterial small multidrug resistance (SMR) family of proteins that pumps quaternary cation compounds (QCC) out of the cell. An attraction of studying multi-ligand resistance systems is that there is promiscuity in substrate ligand recognition, yet still specific in ligand selection. The SMR proteins transport a seemingly wide diversity of compounds with little chemical commonality, yet they still display amazing selectivity; how is this done? The primary SMR protein we study is EmrE (Escherichia coli multi-resistance protein E). This grant aims to continue our research on the SMR family of proteins. In this grant cycle, the specific objectives are: i) Define the ligand-binding site(s) of EmrE. ii) Identify other proteins involved in the complete transport system of moving the toxin completely out of the cell. iii) Begin to define some of the biochemistry for the transport of natural substrates of EmrE. iv) Study the influence of ligand on multimeric state and folding of SMR proteins. v) Evaluate the physiological response of bacteria to QCC compounds.***The long-term goal of these studies is to provide a biochemical and biophysical picture of folding, oligomerization, stability, ligand specificity, function, biochemical mechanisms and physiology of SMR proteins, thus contributing to understanding multi-resistance mechanisms and functionality of integral membrane proteins.  Understanding multi-compound resistance in bacteria is key to the development of improving the efficacy of antiseptic compounds and new antimicrobial agents.  The need is reflected in the use of QCCs.  The global market for industrial and institutional cleaning products will exceed $50 billion by 2018, and biocides and disinfectants also represent more than 10% of the market of water treatment agents used worldwide.**