The ring-shaped structural maintenance of chromosome (SMC) complexes are multi-subunit ATPases that topologically encircle DNA. SMC rings make vital contributions to numerous chromosomal functions, including mitotic chromosome condensation, sister chromatid cohesion, DNA repair, and transcriptional regulation. They are thought to do so by establishing interactions between more than one DNA. Here, we demonstrate DNA-DNA tethering by the purified fission yeast cohesin complex. DNA-bound cohesin efficiently and topologically captures a second DNA, but only if that is single-stranded DNA (ssDNA). Like initial double-stranded DNA (dsDNA) embrace, second ssDNA capture is ATP-dependent, and it strictly requires the cohesin loader complex. Second-ssDNA capture is relatively labile but is converted into stable dsDNA-dsDNA cohesion through DNA synthesis. Our study illustrates second-DNA capture by an SMC complex and provides a molecular model for the establishment of sister chromatid cohesion.

中文翻译：

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通过粘着素环建立DNA-DNA相互作用。

染色体（SMC）复合物的环状结构维持是拓扑上环绕DNA的多亚基ATPase。SMC环为许多染色体功能做出了重要贡献，包括有丝分裂染色体凝结，姐妹染色单体凝聚力，DNA修复和转录调控。人们认为它们是通过在多个DNA之间建立相互作用来实现的。在这里，我们展示了通过纯化的裂变酵母黏附素复合物进行的DNA-DNA束缚。与DNA结合的粘着素可以有效地并在拓扑上捕获第二个DNA，但前提是第二个DNA是单链DNA（ssDNA）。像最初的双链DNA（dsDNA）拥抱一样，第二次ssDNA捕获也是ATP依赖性的，并且严格要求黏附素装载物复合物。Second-ssDNA捕获相对不稳定，但可通过DNA合成转化为稳定的dsDNA-dsDNA内聚力。