Lipid functions in bacterial cell organization

项目概要/摘要：细胞膜可以通过形成离散的 膜微区（microdomain，EMT），如在细胞膜中发现的富含胆固醇和漂浮蛋白的“脂筏”。 真核生物在细菌中，人们对细胞膜的空间组织知之甚少。 因为这个结构域不合成胆固醇或相关的真核脂质， 已经假定它们不包含筏状隔室。Hopanoid脂质是 最接近胆固醇的细菌类似物，我的实验室发现它们促进胆固醇的形成， 在兼性内共生菌Bradyrhizobium diazoefficiens中。这些人有类似的 生物物理特性作为真核生物脂筏和典型的极化，这表明一个链接 和细胞极性之间的联系在这里，我建议评估类阿片介导的 脂质筏具有与真核脂质筏相似的组成，并鉴定出 在这些地区进行协调（项目1）。我们还将检查细胞周期和极性 B中的调节。diazoefficiens，以及它是否受到类鸦片介导的两种 自由生活和宿主相关环境（项目2）。这些项目将有助于发现 细菌膜组织的基本模式，可能与 人类相关微生物，并可能揭示细菌和真核生物之间的新相似之处 亚细胞组织

Project Summary/Abstract: Cellular membranes can be organized by the formation of discrete membrane microdomains (MMs), such as the cholesterol- and flotillin-rich “lipid rafts” found in eukaryotes. In bacteria, little is understood about the spatial organization of the cell membrane. Because this domain does not synthesize cholesterol or related eukaryotic lipids, it traditionally has been assumed that they do not contain raft-like compartments. Hopanoid lipids are the closest bacterial analogs of cholesterol, and my lab has found that they promote formation of MMs in the facultative endosymbiont Bradyrhizobium diazoefficiens. These MMs have similar biophysical properties as eukaryotic lipid rafts and are typically polarized, suggesting a link between raft-like MMs and cell polarity. Here, I propose to assess whether hopanoid-mediated MMs have similar compositions as eukaryotic lipid rafts and identify biological processes that are coordinated in these regions (Project 1). We also will examine cell cycle and polarity regulation in B. diazoefficiens, and whether it is affected by hopanoid-mediated MMs in both free-living and host-associated environments (Project 2). These projects will help discover fundamental paradigms of bacterial membrane organization that are likely to be shared with human-associated microbes, and may uncover new parallels between bacterial and eukaryotic subcellular organization.