Global control of differentiation in Caulobacter

发展计划的正确执行需要个别事件有秩序地进行 时尚。分化细胞必须整合DNA复制、细胞分裂和变化等过程 在形态上。这个项目的长期目标是了解细胞分裂和细胞分化是如何 都被调控并整合在新月弯杆菌中。每个细胞分裂都是不对称的 产生两种不同的细胞类型：活动的丛生细胞和定柄的细胞。只有被跟踪的牢房是 有能力复制DNA并进行分裂。不对称分裂前细胞的一极有鞭毛，一极有鞭毛 在另一极悄悄前进。细胞分裂前不对称性的建立与细胞紧密相连 DNA复制和细胞分裂检查点的周期进程。拟议的研究主要有三个方面 目标。第一个目标是确定负责细胞周期控制的机制 组织。连接细胞分裂和DNA复制的一个检查点是由主细胞周期调节的 响应调节器CtrA。建议通过实验来确定CtrA的活性是如何通过 DNA复制以及细胞如何通过降低细胞分裂为复制检查点做好准备 蛋白质在每个细胞周期的末尾。第二个目标是定义基因和细胞分裂 将极地发育与细胞分裂相结合的检查点机制。Sigma-54的特异性反应 细胞分裂检查点需要调节剂TACA，其作用机制将被确定。 参与检查点控制的TACA依赖基因(S)将被鉴定和研究，并 细胞分裂抑制转导到TACA的机制将被确定。第三个目标是 极细胞器发育蛋白PodJ在菌毛和持持率调节中的作用 合成，被细胞分裂检查点阻止的两个事件。PodJ在本地化中的作用 将确定发育的关键调控因素和PodJ蛋白降解处理的机制， 与细胞分裂有关的基因，将会被研究。这些研究将有助于更好地理解 调节细胞分化的机制。

The correct execution of a developmental program requires that individual events proceed in an orderly fashion. Differentiating cells have to integrate processes such as DNA replication, cell division, and changes in morphology. The long-term goal of this project is to understand how cell division and cell differentiation are regulated and integrated in the bacterium Caulobacter crescentus. Each cell division is asymmetric and produces two different cell types: a motile swarmer cell and a sessile stalked cell. Only the stalked cell is competent to replicate DNA and divide. The asymmetric predivisional cell has a flagellum at one pole and a stalk at the opposite pole. The establishment of asymmetry prior to cell division is tightly coupled to cell cycle progression by DNA replication and cell division checkpoints. The proposed research has three main objectives. The first objective is to identify the mechanisms responsible for the cell cycle control of cell division. One checkpoint that couples cell division to DNA replication is mediated by the master cell cycle response regulator CtrA. Experiments are proposed to determine how the activity of CtrA is regulated by DNA replication and how the cell sets the stage for the replication checkpoint by degrading cell division proteins at the end of every cell cycle. The second objective is to define the genes and the cell division checkpoint mechanism that couple polar development to cell division. The sigma-54 specific response regulator TacA is required for the cell division checkpoint and its mechanism of action will be determined. The TacA-dependent gene(s) involved in checkpoint control will be identified and studied, and the mechanism by which cell division inhibition is transduced to TacA will be determined. The third objective is to investigate the function of the polar _organelle development protein PodJ in regulating pili and holdfast synthesis, two events that are blocked by the cell division checkpoint. The role of PodJ in the localization of critical regulators of development will be determined and the mechanism of PodJ proteolytic processing, which is coupled to cell division, will be investigated. These studies will lead to a better understanding of the mechanisms that regulate cell differentiation.