Roles of molecular interactions in the control of cellular hydration by bacterial osmosensing transporter ProP

分子相互作用在细菌渗透传感转运蛋白 ProP 控制细胞水合中的作用

• 批准号: RGPIN-2017-05160
• 负责人: Wood, Janet
• 金额: $ 2.48万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711365
• 关键词: Roles; molecular; interactions; control; cellular

Physical properties of cellular environments vary over time and space. They include the temperature, the hydrostatic pressure and the osmotic pressure. Changing environmental osmotic pressure causes water to flow into or out of cells, thereby changing their hydration and impairing their functions. Water follows solutes, so water fluxes can be mitigated by moving solutes across the membrane that encloses each cell. Those solutes include salts, amino acid-like compounds and sugars. Osmotic downshocks cause cell swelling and trigger solute release via tension-sensitive membrane channels to avoid cell rupture. Osmotic upshocks cause cell shrinkage and trigger solute uptake via osmosensing transporters to forestall dehydration. We aim to understand how osmotically-induced cell dehydration triggers and modulates solute uptake via osmosensing transporter ProP in Escherichia coli and other bacteria. If fact, our work rendered ProP the paradigmatic osmosensing transporter. The ProP protein is embedded in the membrane that surrounds the cell and exposed on both membrane surfaces. ProP binds solutes available outside the cell and releases them inside the cell. The rate at which ProP pumps solutes into cells (ProP activity) depends on the composition of the membrane in which it is embedded and the salinity of the cellular interior. The membrane composition varies over the cell surface, and ProP concentrates at the ends (the poles) of rod-shaped E. coli cells. We will test the hypothesis that both ProP targeting to the cell poles and ProP activity are controlled by salt-dependent self-association and membrane association of a ProP domain that extends into the cellular interior. Key features of that domain will be identified by changing its structure (through gene editing), then examining the function and cellular location of the resulting ProP variants. Advanced chemical techniques (for example, nuclear magnetic resonance and infrared spectroscopies) and supercomputer-based simulations will be used to analyze how self- and membrane-association influence the structures of ProP and its variants. This will allow us to visualize how the structure of ProP depends on its subcellular location and the osmotic pressure. ProP serves as a paradigm for the study of two fundamental phenomena: osmosensing and protein localization within cells. Many biological processes result from structure-specific (lock and key) interactions between solutes and protein or nucleic acid receptors. We aim to understand different principles that allow cells to detect physical stimuli such as osmotic stress. By deducing how E. coli cells sense and control their own physical properties, we elucidate mechanisms that promote the health and survival of microbes, animals and plants. For example, such mechanisms are central to the survival of bacteria in food and water supplies, kidney cells and crop plants in salty soils.

细胞环境的物理性质随时间和空间而变化。 它们包括温度、静水压力和渗透压。 改变环境渗透压导致水流入或流出细胞，从而改变它们的水合作用并损害它们的功能。 水跟随着溶质流动，因此可以通过移动溶质穿过包围每个细胞的膜来减轻水通量。 这些溶质包括盐、氨基酸样化合物和糖。 渗透性下冲击引起细胞肿胀，并通过张力敏感膜通道触发溶质释放，以避免细胞破裂。 渗透上冲击引起细胞收缩，并触发溶质摄取通过膜敏感转运蛋白，以防止脱水。 我们的目的是了解如何诱导细胞脱水触发和调节溶质的吸收，通过在大肠杆菌和其他细菌中的蛋白质敏感转运蛋白ProP。 事实上，我们的工作使ProP成为典型的生物传感转运体。 ProP蛋白包埋在包围细胞的膜中，并暴露在两个膜表面上。 ProP结合细胞外可用的溶质并将其释放到细胞内。 ProP将溶质泵入细胞的速率（ProP活性）取决于其嵌入的膜的组成和细胞内部的盐度。 细胞表面的膜组成不同，ProP集中在杆状E. coli细胞。 我们将测试的假设，ProP靶向细胞两极和ProP活性控制盐依赖性的自我协会和膜协会的ProP域延伸到细胞内部。 该结构域的关键特征将通过改变其结构（通过基因编辑）来确定，然后检查所得ProP变体的功能和细胞位置。 先进的化学技术（例如，核磁共振和红外光谱）和基于超级计算机的模拟将用于分析自我和膜缔合如何影响ProP及其变体的结构。 这将使我们能够可视化ProP的结构如何取决于其亚细胞位置和渗透压。 ProP作为研究两种基本现象的范例：细胞内的蛋白质定位和细胞内的蛋白质传感。 许多生物过程是由溶质与蛋白质或核酸受体之间的结构特异性（锁和钥匙）相互作用引起的。我们的目标是了解不同的原则，使细胞检测物理刺激，如渗透压。 通过推导E.大肠杆菌细胞感知和控制自己的物理特性，我们阐明了促进微生物，动物和植物健康和生存的机制。 例如，这些机制是细菌在食物和水源、肾细胞和盐性土壤中作物中生存的核心。