Coordinating DNA replication initiation with cell growth: Differential roles for DnaA and SeqA proteins
Coordinating DNA replication initiation with cell growth: Differential roles for DnaA and SeqA proteins
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DOI：
10.1073/pnas.93.22.12206
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发表时间：
1996-10-29
影响因子：
11.1
通讯作者：
Skarstad, K
中科院分区：
文献类型：
--
作者：
Boye, E;Stokke, T;Skarstad, K
我们在这里描述了一种新的方法来分析大肠杆菌复制控制的发展。细胞以低生长速率生长，在这种情况下，细菌细胞周期接近具有G（1）、S和G（2）期的真核细胞的细胞周期：细胞分裂之后依次是没有DNA复制的间隙期、单个染色体的复制、另一间隙期，最后是下一次细胞分裂，这种缓慢生长的细胞的流式细胞术揭示了作为细胞质量的函数的复制起始的时间。数据显示，起始通常与细胞生理学极其紧密地耦合：在野生型细胞中起始时单个细胞团的分布非常窄，变异系数小于9%。此外，野生型和seqA突变体细胞之间的比较显示，在seqA突变体中起始发生在低10-20%的质量下，提供了SeqA是复制起始的良好负调节剂的直接证据。在dnaA（Ts）突变体中，发现了相反的情况：起始时的质量显著增加并且起始时Fell质量的可变性比野生型细胞高得多，与野生型和dnaA（Ts）细胞相反，seqA突变细胞经常在每个细胞分裂周期中经历两次起始事件，并且每个细胞中存在的所有起源都不同步启动，讨论了生长，细胞分裂和DNA复制之间复杂相互作用的影响。
We describe here the development of a new approach to the analysis of Escherichia coli replication control. Cells were grown at low growth rates, in which case the bacterial cell cycle approximates that of eukaryotic cells with G(1), S, and G(2) phases: cell division is followed sequentially by a gap period without DNA replication, replication of the single chromosome, another gap period, and finally the next cell division, Flow cytometry of such slowly growing cells reveals the timing of replication initiation as a function of cell mass. The data show that initiation is normally coupled to cell physiology extremely tightly: the distribution of individual cell masses at the time of initiation in wild-type cells is very narrow, with a coefficient of variation of less than 9%. Furthermore, a comparison between wild-type and seqA mutant cells shows that initiation occurs at a 10-20% lower mass in the seqA mutant, providing direct evidence that SeqA is a bona fine negative regulator of replication initiation, In dnaA(Ts) mutants the opposite is found: the mass at initiation is dramatically increased and the variability in fell mass at initiation is much higher than that for wild-type cells, In contrast to wild-type and dnaA(Ts) cells, seqA mutant cells frequently go through two initiation events per cell division cycle, and all the origins present in each cell are not initiated in synchrony, The implications for the complex interplay amongst growth, cell division, and DNA replication are discussed.