Identification and characterization of factors affecting cytoskeletal proteins--the mediators of bacterial cell shape

项目总结 一般说来，通过细胞骨架调节细菌细胞形状的媒介还不是很清楚。我们将探索 基于三个有希望的观察，细胞骨架和细胞形状的相互作用。首先，我们已经确定了一个 磷脂合成酶(CC1159)，当过表达时，会导致新冠杆菌 通过抑制其定位和功能，将其形状从新月形改变为棒状 中间丝蛋白称为新月体蛋白。第二，过表达催化失活的版本 磷脂合成酶的活性仍然调节细胞形状的改变，这表明表型导致 来自蛋白质之间的相互作用，而不是磷脂水平的升高。第三，细菌双杂交数据 提示我们的磷脂合成酶与自身以及与胞嘧啶三磷酸合成酶(CTPs)相互作用， 当通过与新月体蛋白相互作用过表达时，也会诱导出杆状的形态。人类 新月体蛋白的同系物，中间细丝核层蛋白A/C，与过早衰老和 肌营养不良，我们认为磷脂合成和中间丝之间存在联系。 这可能与它们的人类同源物相似。真核文献中的研究才刚刚开始与 磷脂/鞘磷脂[和糖基磷脂酰肌醇锚定蛋白(GPI-AP)]与中间体 提示我们对新月浑鼠的研究可能与人类有关。另外， 幽门螺杆菌和霍乱弧菌的新月形有助于宿主的定植和致病。 因此，我们的发现可能也与这些人类病原体的细胞形状和致病性有关。

PROJECT SUMMARY In general, mediators of bacterial cell shape via the cytoskeleton are not well understood. We will explore the interplay of the cytoskeleton and cell shape based on three promising observations. First, we have identified a phospholipid synthase (CC1159) that, when overexpressed, causes the bacterium Caulobacter crescentus to change its shape from a crescent to a rod-shaped morphology by inhibiting the localization and function of the intermediate filament protein known as crescentin. Second, overexpression of a catalytically inactive version of the phospholipid synthase still mediates the change in cell shape, suggesting that the phenotype results from a protein-protein interaction instead of elevated levels of a phospholipid. Third, bacterial two-hybrid data suggest that our phospholipid synthase interacts with itself and with cytosine triphosphate synthase (CtpS), which also induces a rod-shaped morphology when overexpressed via interaction with crescentin. Human homologs of crescentin, the intermediate filament nuclear Lamins A/C, are implicated in premature aging and muscular dystrophy, and we suggest a link between phospholipid synthesis and intermediate filaments in C. crescentus that may parallel their human homologs. Research in the eukaryotic literature is just starting to link phospholipids/sphingolipids [and glycosylphosphatidylinositol-anchored proteins (GPI-AP)] with intermediate filaments, suggesting that our investigations in C. crescentus may be relevant to humans. Additionally, Helicobacter pylori's and Vibrio cholerae's crescent shape contributes to host colonization and pathogenesis. Thus, our findings may be also relevant to cell shape and pathogenicity of these human pathogens.