STRUCTURAL PARAMETERS INVOLVED IN METAL RECOGNITION

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。生物控制过渡金属离子的机制及其在细胞调控中的作用已成为金属生物化学研究的重点领域。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。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，我们计划使用XAS来检测镍转运蛋白中的镍位点结构，包括：金属调节蛋白（NikR）、金属转运蛋白（NikABCDE）和金属伴侣蛋白（HypA）——这些蛋白都参与了大肠杆菌中的镍转运，以及它们在幽门螺杆菌中的同源物。细菌（包括人类病原体）的生存能力与所需金属（包括镍）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导致的（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疾病）。此外，对参与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。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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 metals into enzyme active sites. The details of how the metalloproteins recognize, bind and respond to the presence of the requisite metal ions 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. 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 use XAS to examine the structures of Ni sites in nickel trafficking proteins including: a metalloregulator (NikR), a metallotransporter (NikABCDE) and a metallochaperone (HypA)--proteins all involved in nickel trafficking in E. coli, and their homologs in H. pylori. The viability of bacteria, including human pathogens, is linked to the acquisition of required metals (including Ni), 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). 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.