Structural Parameters Involved in Metal Recognition

描述(申请人提供)：生物控制过渡金属离子的机制以及这些金属在细胞调节中的作用已成为矿物生物化学的关键研究领域。生物系统需要特定的金属结合和反应，以避免金属之间在蛋白质表达、特定金属的摄取以及将正确的金属掺入酶活性部位中的串扰。金属蛋白如何识别、结合和响应所需金属离子的存在的细节还没有很好地确定。过渡金属离子尤其如此，其中许多离子具有相似的电荷和离子半径。因此，配位几何构型和配体偏好(至少在氨基酸提供的配体中)似乎在区分过渡金属方面起着重要作用。这项建议寻求使用生物物理方法，目的是描绘在确定金属专一性时涉及的结构参数。这个研究项目的总体目标是了解参与金属运输的金属蛋白中构成金属特异性结合的结构参数，以及相关的蛋白质结构对特定金属结合的反应。为了实现这一目标，我们计划研究金属调节蛋白(NikR)、金属转运蛋白(NikABCDE)和金属配位蛋白(HypB)--这些蛋白都参与了镍在大肠杆菌中的运输。细菌的生存能力，包括人类病原体，与所需金属的获取有关，一些人类疾病已被证明是金属贩运崩溃的结果(例如，铜的威尔逊病和门克斯病，遗传性血色沉着病和其他遗传性铁过载疾病)。因此，对金属贩运的详细了解对于了解金属新陈代谢及其对人类健康的影响非常重要，并需要了解每种所需金属特有的金属调节器、金属转运体和伴侣的运作机制。此外，对金属运输中涉及的结构参数的详细了解可能会导致设计新的抗生素来干扰细菌的金属代谢，这通常是发病所必需的，并培育出对金属具有抗性并可用于生物修复的植物。

DESCRIPTION (provided by applicant): The mechanisms by which organisms control transition metal ions and the roles of these metals in cellular regulation have emerged as key areas of investigation in metallobiochemistry. Specific metal binding and responses are required by biological systems in order to avoid cross talk between metals in the expression of proteins, in the uptake of specific metals, and for the incorporation of the correct metal into enzyme active sites. The details of how the metalloproteins recognize, bind and respond to the presence of the requisite metal ion is not well established. This is particularly true for transition metal ions, many of which have similar charges and ionic radii. Thus, it seems likely that coordination geometry and ligand preferences (at least among the ligands provided by amino acids) play important roles in distinguishing transition metals. This proposal seeks to use biophysical methods aimed at delineating structural parameters that are involved in determining metal specificity. The overall objective of this research project is to understand the structural parameters that underlie metal specific binding, and the related protein structural responses to specific metal binding, in metalloproteins involved in metal trafficking. Toward this goal, we plan to examine the structural parameters involved in a metalloregulator (NikR), a metallotransporter (NikABCDE) and a metallochaperone (HypB)--proteins all involved in nickel trafficking in E. coli. The viability of bacteria, including human pathogens, is linked to the acquisition of required metals, and several human diseases have been shown to result from a breakdown in metal trafficking (e.g., Wilson's and Menkes' diseases for copper, genetic hemochromatosis and other hereditary iron overload disorders for iron). A detailed understanding of metal trafficking is thus important to understanding metal metabolism and its effect on human health, and requires an understanding of mechanisms by which metalloregulators, metal transporters and chaperones specific to each required metal operate. In addition, a detailed understanding of the structural parameters involved in metal-trafficking may lead to the design of new antibiotics that interfere with bacterial metal metabolism, which is frequently essential for pathogenesis, and the development of plants that are resistant to metals and useful in bioremediation.