Diversity Supplement: Physicochemical properties driving membraneless organelle assembly in bacteria

多样性补充：驱动细菌无膜细胞器组装的物理化学特性

基本信息

批准号：
10566672
负责人：
Julie Biteen
金额：
$ 11.84万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-15 至 2025-08-31
项目状态：
未结题

项目摘要

Summary of Parent Grant Recently, breakthrough work has led to a wave of discoveries of biomolecular condensates. Such membraneless organelles that cluster specific biomolecules away from the surrounding cellular milieu have long been theorized and are now experimentally tractable. These dynamic structures contain a wide range of proteins and nucleic acids and assemble through the process of phase separation. While many proteins are prone to phase separation (either by themselves or via complexation with other proteins, nucleic acids, or small molecules), these condensates have primarily been found in eukaryotic cells. Since bacteria do not typically contain membrane-enclosed organelles, we hypothesize that bacteria instead use phase-separated membraneless organelles as novel organizers of their cytoplasm to regulate biochemical activity while they respond to changing environmental conditions. In this proposal, our multidisciplinary team combines state-of-the-art in vitro approaches, in vivo experiments, and in silico modeling and theory to explore the structural organization of the bacterial cytoplasm and characterize phase-separated membraneless organelles in bacteria. We will focus on a candidate protein system, the DNA-binding protein from starved cells (Dps), that drives the organization of the bacterial chromosome and leads DNA to form a separate subcellular compartment within bacterial cells upon stress. We will first study this system’s chemical and mechanical properties, map the phase space for condensate formation, ascertain whether it occurs through spinodal decomposition or nucleation and condensate droplet growth, and determine its kinetics in vitro. Next, we will elucidate how phase separation controls the access of cytoplasmic and nucleoid-associated biomolecules to the bacterial chromosome and image the structure of membraneless DNA-organizing organelles in living bacteria to measure the effect of condensation on chromosome structure and dynamics in vivo. Finally, we will characterize the impact of chromosome phase separation on the mobility of cytoplasmic and DNA-binding proteins in vivo and determine the role of chromosomal condensation in bacterial physiology and survival. Together, our results will define the contributions of the unique physicochemical properties of the bacterial cytoplasm to compartmentalization within these cells. Phase separation provides an alternate mechanism for spatial and functional organization in the bacterial domain of life. Indeed, phase separation is emerging as a universal organizing principle across the tree of life, and our work will ultimately shed light on the origin of life and provide new targets for rationally designed antibiotics.

父母赠款的摘要最近，突破性的工作导致了一系列生物分子冷凝物的发现。这样的将特异性生物分子远离周围的细胞环境聚集的无膜细胞器具有长期以来一直是理论上的，现在可以实验性处理。这些动态结构包含广泛的蛋白质和核酸，并通过相分离过程组装。虽然许多蛋白质是容易分离相（无论是自己还是通过与其他蛋白质，核酸或小的络合分子），这些冷凝物已在真核细胞中发现。由于细菌通常不会包含膜封闭的细胞器，我们假设细菌使用相分离无膜细胞器作为其细胞质的新细胞器，以调节生化活性时应对不断变化的环境条件。在此建议中，我们的多学科团队结合了最新的体外方法，体内实验，以及探索细菌细胞质的结构组织的计算机建模和理论中表征细菌中相分离的无膜细胞器。我们将专注于候选蛋白系统，饥饿细胞（DPS）的DNA结合蛋白，驱动细菌的组织染色体并导致DNA在应激后形成细菌细胞内的单独的亚细胞室。我们将首先研究该系统的化学和机械性能，绘制冷凝水的相空间形成，确定它是通过旋转分解或成核和冷凝水液滴发生的生长并在体外确定其动力学。接下来，我们将阐明相位分离如何控制访问细胞质和核苷相关的生物分子至细菌染色体，并为结构形象活细菌中的无膜DNA组织细胞器，以测量凝结对体内染色体结构和动力学。最后，我们将表征染色体阶段的影响对体内细胞质和DNA结合蛋白的迁移率的分离，并确定细菌生理和生存中的染色体凝结。在一起，我们的结果将定义细菌细胞质独特物理特性对分隔的贡献在这些细胞内。相位分离为空间和功能组织提供了一种替代机制生命的细菌领域。实际上，相位分离正在成为跨越的普遍组织原理生命之树以及我们的工作最终将阐明生活的起源，并为理性提供新的目标设计的抗生素。