Condensin promotes the juxtaposition of DNA flanking its loading site in Bacillus subtilis.
Condensin promotes the juxtaposition of DNA flanking its loading site in Bacillus subtilis.
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DOI：
10.1101/gad.265876.115
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发表时间：
2015-08-01
影响因子：
10.5
通讯作者：
Rudner DZ
中科院分区：
文献类型：
--
作者：
Wang X;Le TB;Lajoie BR;Dekker J;Laub MT;Rudner DZ
在枯草芽孢杆菌中，凝聚素装载在着丝粒parS位点，在那里它包围DNA并使新复制的起源个体化。Wang等人表明，两条染色体臂的并置需要凝聚素募集到近端parS位点。SMC凝聚素复合物在几乎所有生物体中压缩和解析复制的染色体中起着核心作用，但它们如何实现这一点仍然难以捉摸。在枯草芽孢杆菌中，凝聚素装载在着丝粒parS位点，在那里它包围DNA并使新复制的起源个体化。使用染色体构象捕获和细胞学检测，我们表明，凝聚素招聘到原点近端parS网站所需的两个染色体臂的并列。招募异位parS网站促进这些网站侧翼的DNA大轨道对齐。重要的是，在相对臂上插入parS位点表明这些“拉链”相互作用仅发生在相邻的DNA片段之间。总的来说，我们的数据表明，凝聚蛋白解决了复制的起源，促进并列的DNA侧翼parS网站，提请姐妹起源在自己和远离对方。这些结果与一个模型相一致，在该模型中，凝聚素围绕其装载位点两侧的DNA，然后向下滑动，将两臂拴在一起。通过环挤出的拉长缩合可以提供一个可推广的机制，通过该机制，缩合复合物动态地作用于B中的个体化起源。枯草芽孢杆菌，并且当沿真核染色体沿着加载时，在有丝分裂期间将它们分解。
In Bacillus subtilis, condensin is loaded at centromeric parS sites, where it encircles DNA and individualizes newly replicated origins. Wang et al. show that condensin recruitment to origin-proximal parS sites is required for the juxtaposition of the two chromosome arms. SMC condensin complexes play a central role in compacting and resolving replicated chromosomes in virtually all organisms, yet how they accomplish this remains elusive. In Bacillus subtilis, condensin is loaded at centromeric parS sites, where it encircles DNA and individualizes newly replicated origins. Using chromosome conformation capture and cytological assays, we show that condensin recruitment to origin-proximal parS sites is required for the juxtaposition of the two chromosome arms. Recruitment to ectopic parS sites promotes alignment of large tracks of DNA flanking these sites. Importantly, insertion of parS sites on opposing arms indicates that these “zip-up” interactions only occur between adjacent DNA segments. Collectively, our data suggest that condensin resolves replicated origins by promoting the juxtaposition of DNA flanking parS sites, drawing sister origins in on themselves and away from each other. These results are consistent with a model in which condensin encircles the DNA flanking its loading site and then slides down, tethering the two arms together. Lengthwise condensation via loop extrusion could provide a generalizable mechanism by which condensin complexes act dynamically to individualize origins in B. subtilis and, when loaded along eukaryotic chromosomes, resolve them during mitosis.