Structural Basis of Selective Binding and Transport of Metal Ions in Membrane Tra

膜传输中金属离子选择性结合和传输的结构基础

• 批准号: 7263359
• 负责人: Dax Fu
• 金额: $ 32.74万
• 依托单位: BROOKHAVEN SCIENCE ASSOC-BROOKHAVEN LAB
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7263359
• 关键词: Structural; Basis; Selective; Binding; Transport

DESCRIPTION (provided by applicant): Zinc transporters play a central role in regulating zinc homeostasis in cells. Zinc efflux transporters can discriminate Zn2+ from similar cytosolic cations and respond to its fluctuations around a homeostatic set point by pumping excess amounts out of the cytoplasm against steep transmembrane Zn2+ concentration gradients. At present, we have no knowledge of the structure of any zinc transporter. Our long-term goal is to understand the structural basis for selective binding and energized movement of zinc ions in mammalian zinc transporters. This proposed study will focus on cation diffusion facilitators (CDFs) that represent a major family of zinc efflux pumps in diverse organisms from bacteria to mammals. Specifically, we will use x-ray crystallographic- and biochemical-approaches to explore how the zinc affinity, selectivity and mobility are built into the structure of YiiP, a prototypic CDF protein from Escherichia coli. Two specific aims are proposed; (1) To determine the crystal structure of YiiP to reveal a molecular architecture for a model CDF, and, (2) To elucidate the structural basis for binding and transport of Zn2+. This will involve (a) interpreting the crystal structure based on existing biochemical data, (b) determining the functional roles of the observed metal-binding sites in the crystal structure, (c) analyzing the coupling between metal binding and YiiP deprotonation, and, (d) characterizing the kinetics of YiiP motions in response to metal binding. The proposed structural and biochemical analyses will lead to the first x-ray crystallographic solution of a zinc transporter structure and afford a detailed kinetic model for the conformational changes in YiiP that drive the uphill pumping of Zn2+ against an opposing downhill flow of H+. These results will open the door to homology modeling of human CDF structures, thereby setting the stage for structure-based drug design targeting ZnT- 3, a homologous human CDF that is implicated in the pathogenesis of Alzheimer's disease.

描述（由申请人提供）：锌转运蛋白在调节细胞中锌稳态中起核心作用。锌外排转运蛋白可以将Zn 2+与类似的胞质阳离子区分开来，并通过将过量的Zn 2+泵出细胞质对抗陡峭的跨膜Zn 2+浓度梯度来响应其在稳态设定点周围的波动。目前，我们还不知道任何锌转运蛋白的结构。我们的长期目标是了解哺乳动物锌转运蛋白中锌离子选择性结合和能量运动的结构基础。这项拟议的研究将集中在阳离子扩散促进剂（CDF），代表了从细菌到哺乳动物的各种生物体中的锌外排泵的主要家族。具体来说，我们将使用X射线晶体学和生物化学方法来探索锌的亲和力，选择性和流动性是如何构建到YiiP的结构中的，YiiP是一种来自大肠杆菌的原型CDF蛋白。提出了两个具体目标：（1）确定YiiP的晶体结构，以揭示模型CDF的分子结构，以及（2）阐明Zn 2+结合和转运的结构基础。这将涉及（a）基于现有的生物化学数据解释晶体结构，（B）确定晶体结构中观察到的金属结合位点的功能作用，（c）分析金属结合和YiiP去质子化之间的耦合，以及（d）表征响应于金属结合的YiiP运动的动力学。拟议的结构和生化分析将导致第一个X射线晶体学解决方案的锌转运蛋白结构，并提供一个详细的动力学模型的构象变化YiP驱动的上坡泵的Zn 2+对相反的下坡流的H+。这些结果将为人类CDF结构的同源建模打开大门，从而为靶向ZnT- 3的基于结构的药物设计奠定基础，ZnT- 3是一种与阿尔茨海默病发病机制有关的同源人类CDF。