Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
Elife. 2020 May 12;9:e53885. doi: 10.7554/eLife.53885.
Loop extrusion by structural maintenance of chromosomes (SMC) complexes has been proposed as a mechanism to organize chromatin in interphase and metaphase. However, the requirements for chromatin organization in these cell cycle phases are different, and it is unknown whether loop extrusion dynamics and the complexes that extrude DNA also differ. Here, we used egg extracts to reconstitute and image loop extrusion of single DNA molecules during the cell cycle. We show that loops form in both metaphase and interphase, but with distinct dynamic properties. Condensin extrudes DNA loops non-symmetrically in metaphase, whereas cohesin extrudes loops symmetrically in interphase. Our data show that loop extrusion is a general mechanism underlying DNA organization, with dynamic and structural properties that are biochemically regulated during the cell cycle.
结构维持染色体（SMC）复合物的环挤出已被提议作为一种在间期中组织染色质的机制。然而，这些细胞周期阶段对染色质组织的要求不同，并且尚不清楚环挤出动力学和挤出 DNA 的复合物是否也不同。在这里，我们使用卵提取物在细胞周期中重新构建和成像单个 DNA 分子的环挤出。我们表明，环在中期和间期都形成，但具有不同的动态特性。在中期，凝聚素非对称地挤出 DNA 环，而在间期，黏合蛋白对称地挤出环。我们的数据表明，环挤出是一种普遍的 DNA 组织机制，其动力学和结构特性在细胞周期中受到生化调控。
