Rapid pairing and resegregation of distant homologous loci enables double-strand break repair in bacteria.
Rapid pairing and resegregation of distant homologous loci enables double-strand break repair in bacteria.
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DOI：
10.1083/jcb.201505019
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发表时间：
2015-08-03
期刊：
影响因子：
--
通讯作者：
Laub MT
中科院分区：
文献类型：
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作者：
Badrinarayanan A;Le TB;Laub MT
柄杆菌中的双链断裂修复是一个动态过程，其可以独立于DNA复制而发生;修复后近端染色体区域的重新分离需要ParABS系统，而远端区域的重新分离独立于帕拉发生，并且可能没有专用的分离机制。双链断裂（DSB）可导致遗传信息丢失和细胞死亡。虽然通过同源重组的DSB修复已经得到了很好的表征，但细胞内这一过程的空间组织仍然知之甚少，修复后用于染色体再分离的机制也不清楚。在本文中，我们介绍了网站特定的DSB在新月柄杆菌，然后使用延时显微镜可视化随后的染色体动态。受损的基因座在DSB后迅速移动，与它们的同源配偶体配对以使修复成为可能，然后重新聚集到它们的原始细胞位置，而不依赖于DNA复制。起源近端区域重新聚集的ParABS系统的帕拉结构需要重新聚集组装动态响应DSB诱导的运动的起源相关的ParB远离一个细胞极。起源远端区域以不依赖于ParABS的方式重新聚集，而是可能依赖于物理的弹簧样力来分离修复的基因座。总的来说，我们的研究结果提供了一个机械的基础上重新分离的染色体后DSB。
Double-strand break repair in Caulobacter is a dynamic process that can take place independent of DNA replication; resegregation of origin-proximal chromosomal regions after repair requires the ParABS system, whereas resegregation of origin-distal regions occurs independently of ParA and likely without dedicated segregation machinery. Double-strand breaks (DSBs) can lead to the loss of genetic information and cell death. Although DSB repair via homologous recombination has been well characterized, the spatial organization of this process inside cells remains poorly understood, and the mechanisms used for chromosome resegregation after repair are unclear. In this paper, we introduced site-specific DSBs in Caulobacter crescentus and then used time-lapse microscopy to visualize the ensuing chromosome dynamics. Damaged loci rapidly mobilized after a DSB, pairing with their homologous partner to enable repair, before being resegregated to their original cellular locations, independent of DNA replication. Origin-proximal regions were resegregated by the ParABS system with the ParA structure needed for resegregation assembling dynamically in response to the DSB-induced movement of an origin-associated ParB away from one cell pole. Origin-distal regions were resegregated in a ParABS-independent manner and instead likely rely on a physical, spring-like force to segregate repaired loci. Collectively, our results provide a mechanistic basis for the resegregation of chromosomes after a DSB.