Structural Biology of Bacterial Copper Resistance

Rosenzweig98744081。技术上，这个项目的长期目标是从原子上详细了解细菌中铜的动态平衡的分子机制。许多细菌对各种有毒金属离子的抗性系统已经从基因上被鉴定出来，但尚不清楚特定的基因产物是如何在分子水平上结合起来提供抗性的。这项研究的重点是大肠杆菌质粒携带的铜抗性系统PCO，它编码7种不同的蛋白质，包括周质蛋白PcoA、PcoC和PcoE。PcoA、PcoC和PcoE都含有不寻常的蛋氨酸和/或富含组氨酸的序列基序，与任何已知的铜结合基序都不相似。该研究计划结合了X射线结晶学、生物化学和生物物理方法。其具体目标是：1)解决PcoC的Cu(II)、Cu(I)和apo形式的高分辨X射线结构；2)解决PcoE的铜和apo形式的高分辨X射线结构；3)结晶和解决PCoA的结构；以及4)研究PcoA和PcoC之间的相互作用。由此产生的结构信息有望揭示新的铜结合部位，并扩大现有的生物铜中心知识。非技术性铜是微生物的必需元素，但也具有潜在的危害性。由于大量的铜是有毒的，许多由细菌引起的植物疾病都是用含铜的杀菌剂来治疗的。然而，一些细菌已经进化出抵抗铜的系统。为了治疗由这些耐铜细菌引起的作物病害，需要了解铜的抗性机制。已经确定了一些参与抗性系统的蛋白质，但这些蛋白质如何与铜相互作用尚不清楚。该提案中描述的项目侧重于发现这样一个蛋白质家族是如何结合和运输铜的。预计所获得的信息将对农业有重要的实际应用。此外，拟议的工作将扩大铜化学的基础知识。

Rosenzweig98744081. TechnicalThe long term goal of this project is to understand in atomic detail the molecular mechanisms of copper homeostasis in bacteria. A number of bacterial resistance systems for various toxic metal ions have been identified genetically, but it is not known how the specific gene products combine on the molecular level to provide resistance. The proposed research focuses on the Escherichia coli plasmid-borne copper resistance system pco, which encodes 7 different proteins, including the periplasmic proteins PcoA, PcoC, and PcoE. PcoA, PcoC, and PcoE all contain unusual methionine and/or histidine rich sequence motifs which do not resemble any known copper binding motifs. The research plan involves a combination of X-ray crystallographic, biochemical, and biophysical approaches. The specific aims are 1) to solve the high resolution X-ray structures of the Cu(II), Cu(I), and apo forms of PcoC, 2) to solve the high resolution X-ray structures of the copper and apo forms of PcoE, 3) to crystallize and solve the structure of PcoA, and 4) to study interactions between PcoA and PcoC. The resultant structural information is expected to reveal novel copper binding sites and to expand existing knowledge of copper centers in biology.2. Non-technicalCopper is an essential element in microorganisms, but is also potentially harmful. Because large quantities of copper are toxic, a number of plant diseases caused by bacteria are treated with copper containing bacteriocides. Some bacteria have evolved systems to resist copper, however. In order to treat crop afflictions caused by these resistant bacteria, an understanding of the mechanism of copper resistance is required. A number of proteins involved in resistance systems have been identified, but exactly how these proteins interact with copper is not understood. The projects described in this proposal focus on discovering how one such family of proteins binds and transports copper. The information gained is expected to have important practical applications for agriculture. Furthermore, the proposed work will expand fundamental knowledge of copper chemistry.