Lesterlin Christian, Mercier Romain, Boccard Frédéric, Barre François-Xavier, Cornet François
Laboratoire de Microbiologie et de Génétique Moléculaire du CNRS, 118, route de Narbonne, 31062 Toulouse Cedex, France.
EMBO Rep. 2005 Jun;6(6):557-62. doi: 10.1038/sj.embor.7400428.
Recent work has highlighted two main levels of global organization of the Escherichia coli chromosome. Macrodomains are large domains inferred from structural data consisting of loci showing the same intracellular positioning. Replichores, defined by base composition skews, coincide with the replication arms in normal cells. We used chromosome inversions to show that the dif site, which resolves chromosome dimers, only functions when located at the junction of the replichores, whatever their size. This is the first evidence that replichore polarization has a role in chromosome segregation. We also show that disruption of the Ter macrodomain provokes a cell-cycle defect independent from dimer resolution. This confirms the existence of the Ter macrodomain and suggests a role in chromosome dynamics.
近期的研究突出了大肠杆菌染色体全局组织的两个主要层次。宏观结构域是从结构数据推断出的大结构域，由显示相同细胞内定位的基因座组成。由碱基组成偏斜定义的复制子，在正常细胞中与复制臂重合。我们利用染色体倒位表明，用于解决染色体二聚体问题的 dif 位点，无论其大小如何，只有位于复制子的交界处时才起作用。这是复制子极化在染色体分离中起作用的首个证据。我们还表明，Ter 宏观结构域的破坏会引发与二聚体解决无关的细胞周期缺陷。这证实了 Ter 宏观结构域的存在，并暗示其在染色体动态变化中的作用。
