Developmental Control of DNA Replication in Caulobacter

柄杆菌 DNA 复制的发育控制

基本信息

批准号：
7677292
负责人：
LUCILLE SHAPIRO
金额：
$ 20.94万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1994
资助国家：
美国
起止时间：
1994-08-01 至 2010-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Our goal is to identify the mechanisms that integrate temporal and spatial signals to coordinate the initiation of DNA replication, chromosomal origin movement to the cell poles, and the mid-cell assembly of the cell division ring during a bacterial cell cycle. A small number of critical master transcriptional regulators, DnaA, GcrA, and CtrA, control cell cycle progression in Caulobacter. These three proteins are part of a regulatory circuit that together control the expression of genes required for chromosome replication and cytokinesis. We have discovered that DnaA controls both replication initiation and the transcription of cell cycle-regulated genes. DnaA turns on the transcription of GcrA, which, in turn, turns on the transcription of CtrA. GcrA and CtrA oscillate out of phase during the cell cycle to control approximately 150 temporally-regulated genes for polar morphogenesis, DNA methylation, and cell division. DnaA is a critical lynchpin in the regulatory cascade and we will now analyze the temporal control of DnaA availability and activity. We will characterize the genes controlled, in turn, by GcrA and identify a new factor that appears to negatively control the expression of a set of 5 replication enzymes. Caulobacter coordinates the transcription of ctrA with the progression of DNA replication using the differential methylation state of the replicating chromosome. We will now explore the role of DNA methylation in the control of transcription of multiple replication genes all of which have methylation sites in their promoters. Finally, an important question is how chromosome replication and segregation is coordinated with cell division. We have a discovered a unique mechanism that links the MreB actin-dependent movement of the newly replicated origin to the opposite cell pole and the mid-cell positioning of the FtsZ division ring. A ParA-family ATPase, MipZ, in complex with ParB, binds to the origin region and moves with the replicated origin as it transits the length of the cell. Because MipZ is an inhibitor of FtsZ polymerization, the Z-ring can form only at mid-cell once the origins and the accompanying MipZ complex are safely secured at the two cell poles. We will now define the mechanisms that coordinate these events. Defining the regulatory circuitry that drives the bacterial cell cycle has revealed methyltranferases as circuit nodes and as such, targets for antibiotic discovery. Based on this work, we have succeeded in designing a new small molecule antibiotic that is currently in clinical trials.

描述（由申请人提供）：我们的目标是确定整合时间和空间信号的机制，以协调 DNA 复制的启动、染色体起源向细胞极的移动以及细菌分裂过程中细胞分裂环的中细胞组装。细胞周期。少数关键的主转录调节因子 DnaA、GcrA 和 CtrA 控制着柄杆菌的细胞周期进程。这三种蛋白质是调节回路的一部分，共同控制染色体复制和胞质分裂所需基因的表达。我们发现 DnaA 控制着细胞周期调节基因的复制起始和转录。 DnaA 启动 GcrA 的转录，而 GcrA 又启动 CtrA 的转录。 GcrA 和 CtrA 在细胞周期中异相振荡，控制大约 150 个时间调控基因，用于极性形态发生、DNA 甲基化和细胞分裂。 DnaA 是调控级联中的关键关键，我们现在将分析 DnaA 可用性和活性的时间控制。我们将表征由 GcrA 依次控制的基因，并鉴定出一个新因子，该因子似乎负向控制一组 5 种复制酶的表达。茎杆菌利用复制染色体的差异甲基化状态来协调 ctrA 的转录与 DNA 复制的进程。我们现在将探讨 DNA 甲基化在控制多个复制基因转录中的作用，所有这些复制基因的启动子中都有甲基化位点。最后，一个重要的问题是染色体复制和分离如何与细胞分裂协调。我们发现了一种独特的机制，它将新复制起点的 MreB 肌动蛋白依赖性运动与相反的细胞极和 FtsZ 分裂环的细胞中部定位联系起来。 ParA 家族 ATP 酶 MipZ 与 ParB 复合，与起点区域结合，并在穿过细胞长度时与复制起点一起移动。由于 MipZ 是 FtsZ 聚合的抑制剂，因此一旦起始点和伴随的 MipZ 复合物安全地固定在两个细胞极处，Z 环只能在细胞中部形成。我们现在将定义协调这些事件的机制。定义驱动细菌细胞周期的调节回路揭示了甲基转移酶作为回路节点，因此也是抗生素发现的目标。基于这项工作，我们成功设计了一种新的小分子抗生素，目前正处于临床试验阶段。