Valens Michèle, Penaud Stéphanie, Rossignol Michèle, Cornet François, Boccard Frédéric
Centre de Génétique Moléculaire du CNRS, Avenue de la Terrasse, Gif-sur-Yvette, France.
EMBO J. 2004 Oct 27;23(21):4330-41. doi: 10.1038/sj.emboj.7600434. Epub 2004 Oct 7.
We have explored the Escherichia coli chromosome architecture by genetic dissection, using a site-specific recombination system that reveals the spatial proximity of distant DNA sites and records interactions. By analysing the percentages of recombination between pairs of sites scattered over the chromosome, we observed that DNA interactions were restricted to within subregions of the chromosome. The results indicated an organization into a ring composed of four macrodomains and two less-structured regions. Two of the macrodomains defined by recombination efficiency are similar to the Ter and Ori macrodomains observed by FISH. Two newly characterized macrodomains flank the Ter macrodomain and two less-structured regions flank the Ori macrodomain. Also the interactions between sister chromatids are rare, suggesting that chromosome segregation quickly follows replication. These results reveal structural features that may be important for chromosome dynamics during the cell cycle.
我们利用一种位点特异性重组系统，通过基因剖析探索了大肠杆菌染色体结构，该系统可揭示远距离DNA位点的空间邻近性并记录相互作用。通过分析散布在染色体上的位点对之间的重组百分比，我们观察到DNA相互作用局限于染色体的子区域内。结果表明其组织形式为一个由四个宏观结构域和两个结构较松散区域组成的环。由重组效率定义的两个宏观结构域类似于通过荧光原位杂交（FISH）观察到的Ter和Ori宏观结构域。两个新鉴定的宏观结构域位于Ter宏观结构域两侧，两个结构较松散区域位于Ori宏观结构域两侧。此外，姐妹染色单体之间的相互作用很少见，这表明染色体分离在复制后很快就会发生。这些结果揭示了可能对细胞周期中染色体动态变化很重要的结构特征。
