Structural Parameters Involved in Metal Recognition

描述（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结合到酶活性位点中的串扰。金属蛋白如何识别、结合和响应必需金属离子的细节尚未得到很好的确定。对于过渡金属离子尤其如此，它们中的许多具有相似的电荷和离子半径。因此，配位几何和配体偏好（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。该建议寻求使用生物物理方法，旨在描述确定金属特异性所涉及的结构参数。本研究项目的总体目标是了解参与金属运输的金属蛋白中金属特异性结合的结构参数，以及对特定金属结合的相关蛋白质结构响应。为了实现这一目标，我们计划研究与大肠杆菌中镍运输有关的金属调节因子（NikR）、金属转运蛋白（NikABCDE）和金属伴侣蛋白（HypB）的结构参数。细菌（包括人类病原体）的生存能力与所需金属的获取有关，并且已证明几种人类疾病是由于金属贩运的中断而造成的（例如，铜的威尔逊病和门克斯病、遗传性血色素沉着病和其他遗传性铁超载症）。因此，详细了解金属贩运对于了解金属代谢及其对人类健康的影响非常重要，并且需要了解每种所需金属的金属调节剂、金属转运体和伴侣体的运作机制。此外，对金属运输的结构参数的详细了解可能会导致设计干扰细菌金属代谢的新抗生素，这对于致病机制和抗金属植物的发展和生物修复至关重要。

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.