DNA Replication, Bacteria Cell Cycle, and Cell Growth

这个项目的目标是了解DNA的起始 复制与增长率相关联。 理解如何 启动事件的频率被确定，机制 调控DnaA蛋白表达的基因 明白 遗传学和生物化学都被用来 阐明控制表达的调节回路， dnaA操纵子启动子 生长速率调节剂和报警器， 鸟苷四磷酸（ppGpp），抑制转录从 dnaA P2启动子。 这种抑制的分子基础是 在体外进行表征。在抑制基因中有缺陷的突变体 对ppGpp的反应将被检查用于增长率调节， 细胞周期中DNA复制起始的精确时间。 我们将确定dnaA基因是否仍在增长速度下 缺乏ppGpp的细胞中的对照-是否存在生长速率 除了ppGpp之外的控制表达的调节机制 DnaA蛋白质？ 我们将研究DnaA蛋白质-DNA相互作用 通过分离和表征DnaA突变蛋白， 改变DNA结合特异性。 我们将构建一个染色体 oriC两侧基因缺失， 将检查产生的突变体的精确时间损失， 细胞周期 %%% 本研究对细胞分裂过程中关键步骤的控制进行了研究， 应该提供一个基本问题的重要见解， 生物学，以及异常条件，如不受控制的细胞 乘法

The goal of this project is to understand how initiation of DNA replication is coupled to growth rate. To understand how the frequency of the initiation event is determined, the mechanisms that regulate the expression of the DnaA protein must be understood. Both genetics and biochemistry are being used to elucidate the regulatory circuits controlling expression of the dnaA operon promoters. The growth rate regulator and alarmone, guanosine tetraphosphate (ppGpp), inhibits transcription from the dnaA P2 promoter. The molecular basis of this inhibition is being characterized in vitro. Mutants defective in the inhibitory response to ppGpp will be examined for growth rate regulation and precise timing of initiation of DNA replication in the cell cycle. We will determine whether the dnaA gene is still under growth rate control in cells that lack ppGpp - is there a growth rate regulation mechanism other than ppGpp that controls the expression of DnaA protein? We will investigate DnaA protein-DNA interactions by isolation and characterization of DnaA mutant proteins with altered DNA-binding specificities. We will construct a chromosomal mutation with genes on either side of oriC deleted, and the resulting mutant will be examined for loss of precise timing in the cell cycle. %%% This research studies the control of a key step in cell divison and should provide significant insights into a basic question in biology, as well as abberant conditions suchs as uncontrolled cell mutiplication.