Mechanism of Divalent Metal Transport by Nramp-Family Transporters

Nramp 家族转运蛋白的二价金属转运机制

• 批准号: 10796344
• 负责人: RACHELLE GAUDET
• 金额: $ 10.07万
• 依托单位: HARVARD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-01-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10796344
• 关键词: Affect; Affinity; Anemia; Bacteria; Binding; Binding Sites; Biochemical; Biochemistry; Bioinformatics; Biological Models; Biophysical Process; Biophysics; Blood; Brain; Cells; Cellular Membrane; Chemicals; Computer Simulation; Coupled; Coupling; Crystallography; Disease; Distant; Energy Metabolism; Family; Geometry; Goals; Health; Hemochromatosis; Homeostasis; Homologous Gene; Human; Immune System Diseases; Immunity; Ion Transport; Ions; Iron; Knowledge; Liver; Manganese; Metals; Mitochondria; Molecular Conformation; Nramp protein; Organism; Pathway interactions; Physiological; Physiological Processes; Protein Family; Proteins; Protons; Research; Role; Scaffolding Protein; Structure; Thermodynamics; Transition Elements; Variant; commensal microbes; divalent metal; nervous system disorder; oxygen transport; pathogen; protonation; symporter; synergism; therapy design; toxic metal

PROJECT SUMMARY - Mechanism of Divalent Metal Transport by Nramp-Family Transporters Background: Metals like iron and manganese are essential to many physiological processes including oxygen transport and energy metabolism. But excess or deficiency of these ions leads to health issues—including anemia, hemochromatosis and immune or neurological disorders— and their physiological levels are thus tightly regulated. Nramps (natural resistance-associated macrophage proteins) are symporters that import metal ions and protons into cells, and thus are crucial to maintaining transition metal homeostasis. However, the mechanism of coupling between metal ions and protons is unclear. Structures of bacterial Nramps revealed the binding site for the transition metal ion substrate and a proton pathway formed by a polar residue network in the protein scaffold. Furthermore, evidence is emerging that distant Nramp homologs have variations of the metal-binding sequence motifs and transport other metals like Al3+ and Mg2+. Proposed Research: Our goal is two-fold: (i) develop an atomic-level biophysical understanding of the canonical mechanistic features shared by most eukaryotic and bacterial Nramps; and (ii) contrast these features to those in more distant Nramp-like homologs. We combine sequence bioinformatics and other computational approaches with structural and biochemical analyses. In Aim 1, we investigate canonical features of Nramp transporters using a well-established bacterial Nramp model system. We will determine (1a) the metal ion coordination geometry and affinity and selectivity determinants, (1b) whether proton transport is thermodynamically coupled to metal transport, and (1c) how protonation states of the protein alter conformational dynamics. In Aim 2, we investigate divergent Nramp homologs with noncanonical metal-binding and proton-pathway sequence motifs. We examine how these sequence changes affect (2a) proton transport, (2b) metal selectivity, and (2c) metal coordination geometries. Our two aims synergize to provide in- depth biophysical mechanisms and a broad perspective of this important family of transporters. Impact: Both bacterial and mammalian Nramps impact human health. In bacteria, Nramps help commensal microbes acquire essential transition metals and promote colonization by pathogens. Human Nramps are essential for immunity to intracellular pathogens, liver and blood homeostasis, and brain function. This research on metal ion transport by Nramps provides the biochemical and biophysical grounding necessary to explain their essential role in metal homeostasis at the cellular and organismal level. This knowledge could lead to better therapies for metal-related diseases including anemia, hemochromatosis, and many immune and neurological disorders.

项目摘要 - NRAMP家族转运蛋白的二价金属传输机制 背景：铁和锰等金属对于许多物理过程至关重要 包括氧运输和能量代谢。但是这些离子铅的超出或不足 对于健康问题 - 包括贫血，血色素症和免疫或神经系统疾病 - 因此，它们的身体水平受到严格调节。 NRAMP（与自然电阻相关） 巨噬细胞蛋白）是将金属离子和质子进口到细胞中的对比子，因此 对于维持过渡金属稳态至关重要。但是，耦合的机制 金属离子和质子之间尚不清楚。细菌的结构揭示了结合 过渡金属离子底物的位点和由极地居住网络形成的质子途径 在蛋白质支架中。此外，有证据表明遥远的NRAMP同源物具有 金属结合序列基序的变化和运输其他金属（如Al3+和Mg2+）的变化。 拟议的研究：我们的目标是两个方面：（i）建立原子水平的生物物理理解 大多数真核和细菌nramps共有的规范机械特征； （ii） 将这些特征与更遥远的Nramp样同源物的人进行对比。我们结合了序列 生物信息学和其他计算方法，具有结构和生化分析。在 AIM 1，我们使用良好的细菌研究NRAMP转运蛋白的规范特征 NRAMP模型系统。我们将确定（1a）金属离子配位几何和亲和力，以及 选择性确定剂，（1b）质子转运是否与金属耦合 运输和（1C）蛋白质的质子化状态如何改变构象动力学。在AIM 2中， 我们研究了具有非渠道金属结合和质子 - 扎道的发散的NRAMP同源物 序列基序。我们检查了这些序列变化如何影响（2a）质子转运，（2b） 金属选择性和（2C）金属配位几何形状。我们的两个目标协同为提供 - 深度生物物理机制和这个重要转运蛋白家族的广泛观点。 影响：细菌和哺乳动物NRAMP都会影响人类健康。在细菌中，NRAMP有助于 共生微生物获得基本的过渡金属并促进病原体定植。 人Nramp对于对细胞内病原体，肝脏和血液稳态的免疫力至关重要， 和大脑功能。 NRAMP对金属离子传输的这项研究提供了生化和 解释其在细胞中金属稳态中的重要作用所必需的生物物理接地 和有机水平。这些知识可能会导致更好的金属相关疾病疗法 包括贫血，血色素症和许多免疫疾病。