Bioinorganic Explorations of Host-Defense Proteins

项目摘要 过渡金属离子是所有生物体必需的营养物质。这些营养素的可用性起着至关重要的作用 在宿主-微生物相互作用和微生物发病机制中的作用。这项研究的主要目的是 一项旨在阐明宿主防御蛋白钙卫蛋白（CP）如何从 微生物，从而有助于先天免疫反应。CP提供了一个显著的例子， 独特的生物配位化学，与传染病和微生物发病机制有关。 每个CP异源二聚体（S100 A8/S100 A9）表现出用于螯合二价阳离子的六个不同位点，包括 钙（Ca）和过渡金属。我们的中心假设是CP响应生理Ca（II） 梯度调整其与过渡金属的配位化学反应，并调节其作为生物活性物质的生物功能 抗微生物蛋白，剥夺入侵病原体的必需营养金属（如锰、铁、锌）。 所提出的研究是基于初步数据，即在EF-100处人CP（hCP）与Ca（II）的结合， 手域触发过渡金属在S100 A8的界面处形成的位点处的高亲和力螯合 和S100 A9亚基。在目标1中，我们将研究Ca（II）离子如何调节hCP结构并调节其 对过渡金属的亲和力。在目标2中，我们将评估小鼠直系同源物（mCP）如何螯合 过渡金属，从而为CP的文献结果提供所需的分子和生物物理见解 感染的动物模型。在目标3中，我们将研究CP和细菌金属之间的竞争， 锰的运输机械（二）.这些基本的生物无机和生物物理举措构成了 从CP的生物学和医学研究的创新出发，并强调应用的重要性 定量分析和光谱方法来解决人类健康和疾病的核心问题。采取 总之，这些结果将为CP如何促进先天免疫和金属提供新的分子见解。 体内平衡此外，获得金属离子的能力是微生物致病的重要方面， 既能阻断微生物对金属的获取，又能增强宿主对金属的抑制反应， 抗生素发展的机遇。我们预计，从长远来看，我们的工作成果将有助于 指导开发新的抗微生物疗法，靶向这些对宿主至关重要的过程- 病原体相互作用

PROJECT SUMMARY Transition metal ions are essential nutrients for all organisms. The availability of these nutrients plays a critical role in the host-microbe interaction and microbial pathogenesis. The primary objective of this research proposal is to elucidate how the host-defense protein calprotectin (CP) sequesters transition metals from microbes and thereby contributes to the innate immune response. CP provides a remarkable example of unique biological coordination chemistry that is relevant to infectious disease and microbial pathogenesis. Each CP heterodimer (S100A8/S100A9) exhibits six different sites for chelating divalent cations, including calcium (Ca) and transition metals. Our central hypothesis is that CP responds to physiological Ca(II) gradients to tune its coordination chemistry for transition metals and to modulate its biological function as an antimicrobial protein that deprives invading pathogens of essential nutrient metals (e.g. manganese, iron, zinc). The proposed investigations are based on preliminary data that Ca(II) binding by human CP (hCP) at the EF- hand domains triggers high-affinity chelation of transition metals at sites formed at the interface of the S100A8 and S100A9 subunits. In Aim 1, we will investigate how Ca(II) ions modulate hCP structure and tune its affinities for transition metals. In Aim 2, we will evaluate how the murine orthologue (mCP) sequesters transition metals and thereby provide needed molecular and biophysical insights into literature results of CP from animal models of infection. In Aim 3, we will investigate the competition between CP and bacterial metal- transport machinery for manganese(II). These fundamental bioinorganic and biophysical initiatives constitute an innovative departure from biological and medical studies of CP, and highlight the importance of applying quantitative analytical and spectroscopic methods to a problem central to human health and disease. Taken together, the results will provide new molecular insights into how CP contributes to innate immunity and metal homeostasis. Moreover, the ability to acquire metal ions is an important facet of microbial pathogenesis, and both intercepting microbial metal acquisition and boosting the metal-withholding response of the host present opportunities for antibiotic development. We anticipate that the results from our work will, in the long term, help to guide the development of new antimicrobial therapeutics that target these processes central to the host- pathogen interaction.