Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France.
Institut Pasteur, Département Génomes et Génétique, Groupe Régulation spatiale des génomes, 75015 Paris, France; CNRS, UMR 3525, 75015 Paris, France.
Cell. 2018 Feb 8;172(4):771-783.e18. doi: 10.1016/j.cell.2017.12.027. Epub 2018 Jan 18.
As in eukaryotes, bacterial genomes are not randomly folded. Bacterial genetic information is generally carried on a circular chromosome with a single origin of replication from which two replication forks proceed bidirectionally toward the opposite terminus region. Here, we investigate the higher-order architecture of the Escherichia coli genome, showing its partition into two structurally distinct entities by a complex and intertwined network of contacts: the replication terminus (ter) region and the rest of the chromosome. Outside of ter, the condensin MukBEF and the ubiquitous nucleoid-associated protein (NAP) HU promote DNA contacts in the megabase range. Within ter, the MatP protein prevents MukBEF activity, and contacts are restricted to ∼280 kb, creating a domain with distinct structural properties. We also show how other NAPs contribute to nucleoid organization, such as H-NS, which restricts short-range interactions. Combined, these results reveal the contributions of major evolutionarily conserved proteins in a bacterial chromosome organization.
与真核生物一样，细菌基因组并非随机折叠。细菌的遗传信息通常位于一个圆形染色体上，该染色体只有一个复制起点，从该起点复制叉双向朝向相反的末端区域推进。在这里，我们研究了大肠杆菌基因组的高级结构，结果表明，其通过一个复杂且相互交织的接触网络将自身分成两个结构上不同的实体：复制末端（ter）区域和染色体的其余部分。在 ter 之外，凝聚蛋白 MukBEF 和普遍存在的核衣壳相关蛋白（NAP）HU 促进了兆碱基范围内的 DNA 接触。在 ter 内，MatP 蛋白阻止了 MukBEF 的活性，接触仅限于约 280 kb，形成了一个具有独特结构特性的区域。我们还展示了其他 NAP 如何有助于核体组织，例如 H-NS，它限制了短距离相互作用。综合这些结果揭示了主要进化保守蛋白在细菌染色体组织中的贡献。
