Structural maintenance of chromosomes (SMC) complexes are ancient and conserved molecular machines that organize chromosomes in all domains of life. We propose that the principles of chromosome folding needed to accommodate DNA inside a cell in an accessible form will follow similar principles in prokaryotes and eukaryotes. However, the exact contributions of SMC complexes to bacterial chromosome organization have been elusive. Recently, it was shown that the SMC homolog, MukBEF, organizes and individualizes the Escherichia coli chromosome by forming a filamentous axial core from which DNA loops emanate, similar to the action of condensin in mitotic chromosome formation. MukBEF action, along with its interaction with the partner protein, MatP, also facilitates chromosome individualization by directing opposite chromosome arms (replichores) to different cell halves. This contrasts with the situation in many other bacteria, where SMC complexes organise chromosomes in a way that the opposite replichores are aligned along the long axis of the cell. We highlight the similarities and differences of SMC complex contributions to chromosome organization in bacteria and eukaryotes, and summarize the current mechanistic understanding of the processes.

中文翻译：

---

SMC 复合物通过纵向压缩来组织细菌染色体。

染色体结构维持 (SMC) 复合物是古老且保守的分子机器，可在生命的所有领域中组织染色体。我们提出，在细胞内以可接近的形式容纳 DNA 所需的染色体折叠原则将遵循原核生物和真核生物中的类似原则。然而，SMC 复合物对细菌染色体组织的确切贡献一直难以捉摸。最近，有研究表明，SMC 同源物 MukBEF 通过形成一个丝状轴核心来组织和个体化大肠杆菌染色体，从该轴核心发出 DNA 环，类似于凝聚素在有丝分裂染色体形成中的作用。MukBEF 作用，以及它与伴侣蛋白 MatP 的相互作用，还通过将相反的染色体臂（复制体）引导到不同的细胞半部来促进染色体个体化。这与许多其他细菌的情况形成鲜明对比，其中 SMC 复合物以相反的复制体沿细胞长轴排列的方式组织染色体。我们强调了 SMC 复合物对细菌和真核生物染色体组织的贡献的异同，并总结了目前对该过程的机制理解。