Zinc Transporters and Intracellular Zinc Trafficking

锌转运蛋白和细胞内锌贩运

• 批准号: 6983761
• 负责人: David J Eide
• 金额: $ 16.58万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6983761
• 关键词: Saccharomyces cerevisiae; endoplasmic reticulum; intracellular transport; ion transport; transport proteins; vesicle /vacuole; zinc

DESCRIPTION (provided by applicant): Zinc is essential for all organisms. Zinc is a catalytic cofactor of over 300 enzymes and is a critical component of structural motifs such as zinc fingers. Therefore, cells require efficient mechanisms for the accumulation of zinc. Many zinc-dependent proteins are either secreted or localized to the interior of intracellular organelles such as those of the secretory pathway and mitochondria. Therefore, efficient mechanisms are also needed to distribute zinc into intracellular compartments. In contrast, excess zinc can be toxic to cells. This toxicity may be due to the binding of zinc to inappropriate sites in proteins or cofactors. For example, excess zinc can interfere with mitochondrial aconitase activity and impair respiration. The essential yet toxic nature of zinc necessitates precise homeostatic mechanisms to control the intracellular levels of "free", i.e., loosely bound or labile, zinc. We currently know little about intracellular zinc transport and zinc sequestration. We are studying these processes using the yeast Saccharomyces cerevisiae as a model eukaryotic cell. Our studies have raised four central hypotheses that are the foundation of this proposal: 1) The yeast vacuole, the lysosome-like compartment of the yeast cell, plays an important role in storing zinc in replete cells for later use under conditions of zinc deficiency. 2) The vacuole acts as a zinc buffer to control zinc levels in the cytosol and other compartments when the intracellular labile zinc pool changes in response to perturbations in zinc homeostasis. 3) The Msc2 protein, a member of the ubiquitous CDF family of metal ion transporters, is responsible for transporting zinc into the endoplasmic reticulum to supply the metal to secreted and resident proteins in the secretory pathway. 4) Additional transporters are also present in the ER of yeast that transport zinc into the secretory pathway. To test these hypotheses, we propose a multifaceted approach, using a synergistic combination of genetic, molecular biology, cell biology, biochemistry, and bioinorganic chemistry tools, to define the mechanisms and roles of intracellular zinc transport in yeast.

描述（由申请人提供）：锌对于所有生物体都是必需的。锌是 300 多种酶的催化辅因子，也是锌指等结构基序的关键组成部分。因此，细胞需要有效的锌积累机制。许多锌依赖性蛋白被分泌或定位于细胞内细胞器的内部，例如分泌途径和线粒体的细胞器。因此，还需要有效的机制将锌分配到细胞内区室中。相反，过量的锌可能对细胞有毒。这种毒性可能是由于锌与蛋白质或辅因子中不适当的位点结合所致。例如，过量的锌会干扰线粒体乌头酸酶活性并损害呼吸。锌的必需但有毒的性质需要精确的稳态机制来控制“游离”锌（即松散结合或不稳定的锌）的细胞内水平。目前我们对细胞内锌转运和锌螯合知之甚少。我们正在使用酿酒酵母作为模型真核细胞来研究这些过程。我们的研究提出了四个中心假设，它们是该提议的基础：1）酵母液泡（酵母细胞的溶酶体样区室）在将锌储存在充足的细胞中以供以后缺锌条件下使用方面发挥着重要作用。 2）当细胞内不稳定的锌库因锌稳态的扰动而发生变化时，液泡充当锌缓冲剂来控制细胞质和其他区室中的锌水平。 3) Msc2 蛋白是普遍存在的金属离子转运蛋白 CDF 家族的成员，负责将锌转运到内质网，为分泌途径中的分泌蛋白和驻留蛋白提供金属。 4) 酵母的内质网中还存在其他转运蛋白，将锌转运至分泌途径。为了检验这些假设，我们提出了一种多方面的方法，利用遗传、分子生物学、细胞生物学、生物化学和生物无机化学工具的协同组合，来定义酵母细胞内锌转运的机制和作用。