The segregation of the Escherichia coli origin and terminus of replication
The segregation of the Escherichia coli origin and terminus of replication
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DOI：
10.1046/j.1365-2958.2002.03234.x
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发表时间：
2002-11-01
影响因子：
3.6
通讯作者：
Austin, S
中科院分区：
文献类型：
--
作者：
Li, YF;Sergueev, K;Austin, S
大肠杆菌染色体复制叉被拴在细胞中心。两个相反的模型描述了染色体是如何分离的。在挤压-捕获模型中，新复制的DNA从分叉向细胞两极双向输送，在每个细胞中形成新的染色体。从起源开始，染色体区域在复制过程中逐渐与姐妹篇分离。末端最后分离。在姐妹染色体内聚力模型中，复制产生了沿着大部分长度配对的姐妹染色体。起点和大多数其他染色体区域保持配对，直到复制周期的后期，并且全部分离在一起。我们使用显微镜和流式细胞术相结合，以确定起源和末端分离的细胞周期的关系。起源隔离往往紧随其后的启动，在强有力的支持挤出捕获模型。起始序列和末端序列的空间分布也符合该模型。末端分离发生在细胞周期的极晚期，因为子细胞分离。当隔膜开始内陷时，完成的姐妹染色体的末端在细胞中心暂时分开，在细胞的相对两侧。这可以促进染色体之间的拓扑连锁的解析。
Escherichia coli chromosome replication forks are tethered to the cell centre. Two opposing models describe how the chromosomes segregate. In the extrusion-capture model, newly replicated DNA is fed bi-directionally from the forks toward the cell poles, forming new chromosomes in each cell half. Starting with the origins, chromosomal regions segregate away from their sisters progressively as they are replicated. The termini segregate last. In the sister chromosome cohesion model, replication produces sister chromosomes that are paired along much of their length. The origins and most other chromosomal regions remain paired until late in the replication cycle, and all segregate together. We use a combination of microscopy and flow cytometry to determine the relationship of origin and terminus segregation to the cell cycle. Origin segregation frequently follows closely after initiation, in strong support of the extrusion-capture model. The spatial disposition of the origin and terminus sequences also fits this model. Terminus segregation occurs extremely late in the cell cycle as the daughter cells separate. As the septum begins to invaginate, the termini of the completed sister chromosomes are transiently held apart at the cell centre, on opposite sides of the cell. This may facilitate the resolution of topological linkages between the chromosomes.