In bacteria, ParABS systems and structural maintenance of chromosome (SMC) condensin‐like complexes are important for chromosome segregation and organization. The rod‐shaped Myxococcus xanthus cells have a unique chromosome arrangement in which a scaffold composed of the BacNOP bactofilins and PadC positions the essential ParB∙parS segregation complexes and the DNA segregation ATPase ParA in the subpolar regions. We identify the Smc and ScpAB subunits of the SMC complex in M. xanthus and demonstrate that SMC is conditionally essential, with Δsmc or ΔscpAB mutants being temperature sensitive. Inactivation of SMC caused defects in chromosome segregation and organization. Lack of the BacNOP/PadC scaffold also caused chromosome segregation defects but this scaffold is not essential for viability. Inactivation of SMC was synthetic lethal with lack of the BacNOP/PadC scaffold. Lack of SMC interfered with formation of the BacNOP/PadC scaffold while lack of this scaffold did not interfere with chromosome association by SMC. Altogether, our data support that three systems function together to enable chromosome segregation in M. xanthus. ParABS constitutes the basic and essential machinery. SMC and the BacNOP/PadC scaffold have different yet redundant roles in chromosome segregation with SMC supporting individualization of daughter chromosomes and BacNOP/PadC making the ParABS system operate more robustly.

中文翻译：

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SMC 和 bactofilin/PadC 支架在黄色粘球菌的染色体分离和组织方面具有独特但冗余的功能。

在细菌中，ParAB S系统和染色体（SMC）凝聚素样复合物的结构维持对于染色体分离和组织很重要。杆状黄色粘液球菌细胞具有独特的染色体排列，其中由 BacNOP bactofilins 和 PadC 组成的支架将基本的 ParB∙ parS分离复合物和 DNA 分离 ATPase ParA 定位在亚极区。我们在M. xanthus 中鉴定了 SMC 复合体的 Smc 和 ScpAB 亚基，并证明 SMC 是有条件地必不可少的，Δ smc或 Δ scpAB突变体对温度敏感。SMC 的失活导致染色体分离和组织缺陷。缺乏 BacNOP/PadC 支架也会导致染色体分离缺陷，但这种支架对于生存能力不是必需的。由于缺乏 BacNOP/PadC 支架，SMC 的失活是合成致死的。缺乏 SMC 会干扰 BacNOP/PadC 支架的形成，而缺乏这种支架不会干扰 SMC 的染色体关联。总之，我们的数据支持三个系统共同作用以实现M. xanthus 中的染色体分离。PARAB小号构成基本和必不可少的机器。SMC 和 BacNOP/PadC 支架在染色体分离中具有不同但冗余的作用，SMC 支持子染色体和 BacNOP/PadC 的个性化，使 ParABS 系统运行更加稳健。