Structural Parameters Involved in Metal Recognition

描述（由申请人提供）：生物体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金属生物化学研究的关键领域。生物系统需要特异性金属结合和反应，以避免蛋白质表达中金属之间的串扰，吸收特定金属，并将正确的金属掺入酶活性位点。关于金属蛋白如何识别、结合和响应所需金属离子的细节还没有很好地确定。对于过渡金属离子尤其如此，其中许多具有相似的电荷和离子半径。因此，似乎可能的是，配位几何形状和配体偏好（至少在由氨基酸提供的配体中）在区分过渡金属中起重要作用。该提案寻求使用生物物理方法，旨在描绘参与确定金属特异性的结构参数。本研究项目的总体目标是了解金属特异性结合的结构参数，以及参与金属贩运的金属蛋白对特异性金属结合的相关蛋白质结构反应。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）和金属伴侣蛋白（HypB）的结构参数，这些蛋白都参与了大肠杆菌中镍的转运。杆菌包括人类病原体在内的细菌的生存能力与所需金属的获得有关，并且已经证明，几种人类疾病是由金属贩运的中断引起的（例如，威尔逊和门克斯病的铜，遗传性血色素沉着症和其他遗传性铁过载疾病的铁）。因此，对金属贩运的详细了解对于了解金属代谢及其对人类健康的影响非常重要，并且需要了解金属调节剂、金属转运蛋白和针对每种所需金属的分子伴侣的运作机制。此外，详细了解金属贩运所涉及的结构参数可能会导致设计新的抗生素，干扰细菌的金属代谢，这往往是必不可少的发病机制，和发展的植物，耐金属和有用的生物修复。

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.