Molecular Mechanisms of Organelle Formation in Bacteria

项目摘要 脂质结合的细胞器被吹捧为真核生物的一个定义特征， 结构上原始的细菌细胞。然而，许多细菌使用脂质结合的细胞器来执行 必要的，有时是有毒的，生物化学反应在一个区隔的方式。我的团队使用 趋磁细菌的磁小体细胞器作为理解的机制基础的模型 细胞器的形成和功能。磁小体是细胞的脂质双层内陷 膜具有独特的蛋白质含量，其中纳米大小的铁基磁性晶体是 制作。单个磁小体在肌动蛋白样细胞骨架的帮助下排列成链， 这使得趋磁细菌能够利用地磁场作为低氧环境的简单指南。的 磁小体的细胞生物学特性使其成为了解细胞器分子基础的理想材料 研究细菌的生物发生，也许还能揭示真核细胞器的进化起源。磁 磁小体的物理性质使其成为生物医学发展的有吸引力的目标 应用，包括它们作为磁共振成像的造影剂、作为药物递送载体的用途 和作为高温杀死肿瘤细胞的介质。除了磁小体，我的团队最近 发现了一种新的铁积累脂质结合的细胞器，称为铁小体。铁小体形成 通过少量基因的作用，在多种细菌中发现，包括 肠道微生物组和机会致病菌。本提案中概述的研究计划将利用 我的团队中的专业知识和现有知识，以探索磁小体的最关键领域， 铁小体生物学首先，我们将集中在细胞生物学机制，使形成和 磁小体的亚细胞组织。我们将定义生物发生所需的最小组件 揭示了蛋白质定位于磁小体的模式和动力学 并研究所需肌动蛋白样细胞骨架的生化和生物物理特征 磁小体的组织。其次，我们将研究铁的生物矿化机制， 磁小体我们将揭示与成核有关的蛋白质的相互作用、活性和功能 和磁性颗粒的生长，并将开发简化的体外系统，以确定动力学和化学 生物矿化的要求。最后，我们将利用这个项目期间，发展铁小体成为一个 用于细菌细胞器研究的替代和鲁棒模型。我们将确定 铁小体膜生物发生、蛋白质分选和铁转运，并平行地定义了它们的生理功能。 在相关微生物中发挥作用。这些方法的结合将揭示演变， 细菌细胞器的机械多样性，同时为它们在应用中的使用提供更合理的基础。 设置.

Project Abstract Lipid-bounded organelles are touted as a defining feature of eukaryotes and one which is absent from the architecturally primitive cells of bacteria. However, numerous bacteria use lipid-bounded organelles to execute essential, and at times toxic, biochemical reactions in a compartmentalized fashion. My group uses the magnetosome organelles of magnetotactic bacteria as a model for understanding the mechanistic basis of organelle formation and function in bacteria. Magnetosomes are lipid-bilayer invaginations of the cell membrane with a unique protein content, within which nanometer-sized iron-based magnetic crystals are produced. Individual magnetosomes are arranged into a chain with the help of an actin-like cytoskeleton, thus allowing magnetotactic bacteria to use geomagnetic fields as a simple guide for low oxygen environments. The cell biological features of magnetosomes make them ideal for understanding the molecular basis of organelle biogenesis in bacteria and, perhaps, uncover the evolutionary origins of eukaryotic organelles. The magnetic and physical properties of magnetosomes make them attractive targets for the development of biomedical applications including their use as contrast agents for magnetic resonance imaging, as drug delivery vehicles and as a medium for hyperthermic killing of tumor cells. In addition to magnetosomes, my group has recently discovered a novel iron-accumulating lipid-bounded organelle named the ferrosome. Ferrosomes are formed through the action of a small number of genes and are found in diverse bacteria including resident members of the gut microbiome and opportunistic pathogens. The research program outlined in this proposal will leverage the expertise and existing knowledge within my group to explore the most critical areas of magnetosome and ferrosome biology. First, we will focus on the cell biological mechanisms that allow for formation and subcellular organization of magnetosomes. We will define the minimal components required for the biogenesis of the magnetosome membrane, uncover the modes and dynamics of protein localization to magnetosomes and study the biochemical and biophysical characteristics of the actin-like cytoskeleton required for organization of magnetosomes. Second, we will investigate the mechanisms of iron biomineralization within magnetosomes. We will uncover the interactions, activity and function of proteins implicated in the nucleation and growth of magnetic particles and will develop simplified in vitro systems to define the kinetics and chemical requirements for biomineralization. Finally, we will use this project period to develop ferrosomes into an alternate and robust model for the study of bacterial organelles. We will determine the mechanisms of ferrosome membrane biogenesis, protein sorting and iron transport and in parallel define their physiological function in relevant microorganisms. The combination of these approaches will shed light on the evolution and mechanistic diversity of bacterial organelles while providing a more rational basis for their use in applied settings.