GENERATION OF ASYMMETRY DURING CAULOBACTER DEVELOPMENT

茎杆菌发育过程中不对称性的产生

• 批准号: 2749924
• 负责人: JAMES W GOBER
• 金额: $ 22.81万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2749924
• 关键词: Caulobacter; DNA replication; bacterial genetics; cell cycle; enzyme activity; flagellum; gene expression; genetic transcription; histidine; microorganism culture; protein kinase; transcription factor

The bacterium Caulobacter crescentus undergoes a simple cellular differentiation within each cell cycle. Cell division generates two distinct cell types: a motile swarmer cell and a sessile stalked cell. These two cell types differ with respect to their relative programs of gene expression and DNA replication. The generation of asymmetry upon cell division is a fundamental aspect of development in diverse organisms, including Drosophila, nematodes and fungi. Caulobacter is a particularly facile organism for the examination of both cell cycle and cellular differentiation events. In progeny stalked cells, the components of the polar flagellum are expressed under cell cycle control and assembled at the pole of the pre divisional cell that lies opposite the stalk. Two well-defined developmental checkpoints regulate flagellar morphogenesis. First, the transcription of early flagellar genes is triggered bu an unknown cell cycle event that is linked to the initiation of DNA replication. Later in the cell cycle, the transcription of late flagellar genes is activated by a cell division event. This later event results in the compartmentalized transcription of both late and early flagellar genes and is attributable to the swarmer pole specific activation of the transcription factor F1bD and its cognate sensor kinase, F1bE. F1bE kinase activity is activated by localizing to the midcell and stalked pole of the pre divisional cell. The overall objectives of this proposal are to define the mechanisms that couple cell cycle events to flagellar biogenesis. Experiments are proposed that for the most part focus on the activation of the sensor histidine kinase F1bE and its role in regulating temporal and spatial transcription. In addition, in order to explore the coupling of DNA replication to early flagellar gene transcription, experiments are described which are designed to identify the alternative sigma factor that directs the transcription of these genes. To accomplish this, a mutational analysis of F1bE will be performed to define sequences important for localization, autophosphorylation, F1bD kinase and phosphatase activities. Genetic identification and characterization of proteins that direct F1bE to the midcell and stalked pole of the pre divisional cell will be performed. Also proposed are experiments designed to identify the cellular cues that regulate temporal and spatial transcription and determine the molecular basis of compartment specific transcription. Lastly, the transcription factor that regulates the temporal expression of early flagellar genes will be isolated and characterized.

细菌caulobacter Crescentus经历了简单的细胞 每个细胞周期内的分化。 细胞分裂产生两个 独特的细胞类型：一个动机蜂窝细胞和一个无柄茎细胞。 这两种细胞类型在其相对程序的不同之处 基因表达和DNA复制。不对称产生 细胞分裂是多元化发展的基本方面 包括果蝇，线虫和真菌在内的生物。花椰菜是 特别容易检查细胞周期和 细胞分化事件。在后代茎细胞中，成分 极性鞭毛的表达在细胞周期控制下， 组装在位于对面的前分区电池的极点 茎。两个定义明确的发育检查站调节鞭毛 形态发生。首先，早期鞭毛基因的转录是 触发了一个未知的单元周期事件，该事件链接到 DNA复制的启动。 在细胞周期的后期，晚期鞭毛基因的转录为 被细胞分裂事件激活。以后的事件导致 晚期和早期鞭毛基因的分隔转录 并且归因于蜂群的特异性激活 转录因子F1BD及其同源传感器激酶F1BE。 F1BE 激酶活性通过定位到中心和茎杆来激活 前部细胞。该提议的总体目标是 定义将夫妇周期事件与鞭毛的机制 生物发生。提出了实验，大部分都集中在 传感器组氨酸激酶F1BE的激活及其在 调节时间和空间转录。另外，为了 探索DNA复制与早期鞭毛基因的耦合 介绍了转录，旨在识别的实验 指导这些转录的替代sigma因子 基因。为此，对F1BE的突变分析将是 执行以定义对本地化很重要的序列， 自磷酸化，F1BD激酶和磷酸酶活性。遗传 将F1BE引导至的蛋白质的识别和表征 将执行前分层细胞的中间细胞和茎杆。 还提出了旨在识别细胞提示的实验 调节时间和空间转录，并确定 隔室特异性转录的分子基础。最后， 调节早期时间表达的转录因子 鞭毛基因将被隔离和表征。