BIOCHEMISTRY AND RADIATION EFFECT DURING THE CELL CYCLE

这个项目的总体目标是调查重复 关于大肠杆菌细胞的过程，特别是关于启动和 染色体DNA的复制，细胞分裂的控制和过程， DNA复制和细胞分裂之间的协调 周而复始。因为决定启动频率的机制 染色体复制是细胞周期中的关键调控步骤， 控制起源于染色体的起始ORIC的研究是 强调。研究计划分为两个基本领域： 生理学研究旨在确定协调的元素 体内、外染色体复制与细胞生长周期的关系 OricC-DNA复制的分子生物学研究。许多 体内和体外项目将采用各种不同的 微小染色体，即从居民那里复制的小DNA分子 Oricc的副本。具体项目有：1)确定时间是否 可以调控大肠杆菌中染色体复制的起始 按所需活动复合体的组成部分进行积极的 入会仪式。最近的发现导致了一种试验性的 这将使这个问题能够得到回答的战略。会是 例如，确定是否明显没有重复利用 用于在oricC上引发的引发络合物是 体内调控系统。2)比较以下各项的复制属性 质粒驱动染色体与oricC驱动染色体共同决定 OricC起源复合体是否具有增长的独特属性 耦合起爆频率调节器。3)表征动力学 单项蛋白质的合成、细胞含量、稳定性和分离 已知与启动和/或复制相关。实验是 计划将这些发现与阳性的预测属性联系起来 监管要素。第二系列实验涉及比较 微染色体DNA复制的体内外分析。这个 在复制过程中染色体进行的中间体将 与拓扑需求的分析一起确定 复制。在复制过程中早期形成的分子物种 将对体外和体内进行详细的检测。

The overall objective of this project is to investigate the duplication process of E. coli cells with particular regard to the initiation and replication of chromosomal DNA, the control and process of cel division, and the coordination between DNA replication and the celllar division cycle. Since the mechanisms which determines the frequency of initiation of chromosome replication is a key regulatory step in the cell cycle, studies on the control of initiation from the chromosomal origin, oriC, are emphasized. The research plan is divided into two basic areas: physiological studies aimed at identifying the elements which coordinate chromosome replication with the cellular growth cycle in vivo, and in vitro studies on the molecular biology of oricC-directed DNA replication. Many of the projects in vivo and in vitro will employ a variety of minichromosomes, i.e., small DNA molecules which replicate from a resident copy of oricC. The specific projects are: 1) To determine if the timing of initiation of chromosome replication in E. coli could be regulated positively by components of the complex of activities required for initiation. Recent findings have led to the development of an experimental strategy which will enable this question to be answered. It will be determined, for instance, whether the apparent absence of reutilization of initiation complexes for initiation at oricC is the basis for the regulatory system in vivo. 2) To compare replication properties of plasmid-driven chromosomes with oricC-driven chromosomes to determine whether the oricC origin-complex possesses unique properties of a growth coupled initiation frequency regulator. 3) To characterize the kinetics of synthesis, cellular content, stability and segretion of individual proteins known to be associated with initiation and/or replication. Experiments are planned to relate these findings to the prediced properties of positive regulatory elements. The second series of experiments involves comparative analyses of minichromosome DNA replication in vitro and in vivo. The intermediates through which mninchromosomes progess during replication will be determined, along with an analysis of topological requirements for replication. The molecular species which form early during replication in vitro and in vivo will be examined in detail.