The tripartite ParABS system mediates chromosome segregation in a wide range of bacteria. Dimeric ParB was proposed to nucleate on parS sites and spread to neighboring DNA. However, how properly distributed ParB dimers further compact chromosomal DNA into a higher-order nucleoprotein complex for partitioning remains poorly understood. Here, using a single-molecule approach, we show that tens of Bacillus subtilis ParB (Spo0J) proteins can stochastically multimerize on and stably bind to nonspecific DNA. The introduction of CTP promotes the formation and diffusion of the multimeric ParB along DNA, offering an opportunity for ParB proteins to further forgather and cluster. Intriguingly, ParB multimers can recognize parS motifs and are more inclined to remain immobile on them. Importantly, the ParB multimer features distinct capabilities of not only bridging two independent DNA molecules but also mediating their transportation, both of which are enhanced by the presence of either CTP or parS in the DNA. These findings shed new light on ParB dynamics in self-multimerization and DNA organization and help to better comprehend the assembly of the ParB-DNA partition complex.

中文翻译：

---

单分子分析揭示的随机多聚 ParB 协调 DNA 组装

三方 ParABS 系统介导多种细菌的染色体分离。二聚体 ParB 被提议在 parS 位点上成核并扩散到相邻的 DNA。然而，如何正确分布的 ParB 二聚体进一步将染色体 DNA 压缩成更高阶的核蛋白复合物以进行分配仍然知之甚少。在这里，我们使用单分子方法，表明数十种枯草芽孢杆菌 ParB (Spo0J) 蛋白可以随机多聚化并稳定结合非特异性 DNA。CTP 的引入促进了多聚 ParB 沿 DNA 的形成和扩散，为 ParB 蛋白进一步聚集和聚集提供了机会。有趣的是，ParB 多聚体可以识别 parS 基序，并且更倾向于在它们上保持不动。重要的，ParB 多聚体具有独特的能力，不仅可以桥接两个独立的 DNA 分子，还可以介导它们的运输，这两者都因 DNA 中 CTP 或 parS 的存在而增强。这些发现为自多聚化和 DNA 组织中的 ParB 动力学提供了新的启示，并有助于更好地理解 ParB-DNA 分区复合物的组装。