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.

中文翻译：

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通过类核蛋白和凝聚蛋白对大肠杆菌染色体进行多尺度结构化。

与真核生物一样，细菌基因组不是随机折叠的。细菌遗传信息通常携带在具有单一复制起点的圆形染色体上，从该复制起点，两个复制叉向相反的末端区域双向前进。在这里，我们研究了大肠杆菌基因组的高阶结构，显示其通过复杂且相互交织的接触网络划分为两个结构不同的实体：复制末端 (ter) 区域和染色体的其余部分。在 ter 之外，凝聚素 MukBEF 和无处不在的类核蛋白 (NAP) HU 促进了兆碱基范围内的 DNA 接触。在 ter 内，MatP 蛋白阻止 MukBEF 活动，并且接触限制在 ~280 kb，创建具有不同结构特性的域。我们还展示了其他 NAP 如何促进类核组织，例如限制短程相互作用的 H-NS。综合起来，这些结果揭示了细菌染色体组织中主要进化保守蛋白质的贡献。