Lipid functions in bacterial cell organization

项目摘要/摘要：细胞膜可按离散形式组织 膜微域(MMS)，例如在 真核生物。在细菌中，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，所以它传统上 已经假定它们不包含木筏状的隔间。类霍帕尼诺类脂质是 与胆固醇最接近的细菌类似物，我的实验室发现它们促进 MMS在兼性内共生菌重氮慢生根瘤菌中的应用。这些彩信有类似的 生物物理性质与真核脂筏相似，并且通常是极化的，这表明存在联系 在浮筏状的MMS和细胞极性之间。在这里，我建议评估类霍帕尼介导的 MMS具有与真核细胞脂筏相似的成分，并识别 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 重氮杆菌的调控以及是否受到霍帕尼类物质介导的MMS的影响 自由生活和与宿主相关的环境(项目2)。这些项目将有助于发现 细菌膜组织的基本范例可能与 人类相关微生物，并可能发现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.