欧洲分子生物学实验室Christian H. Haering和Sebastian Eustermann研究组合作发现，维持和供给机制通过凝聚素驱动定向 DNA 环挤出。2022年6月3日，国际知名学术期刊《科学》发表了这一成果。

他们表明，活性凝集素复合物将 DNA 环的碱基瞬时困在两个单独的腔室中。单分子成像和冷冻电镜表明，在第一个腔室中推定的动力冲程运动在三磷酸腺苷结合后将 DNA 送入染色体结构维持 (SMC) -kleisin 环，而第二个腔室则保持在相同 DNA 双螺旋的上游。解锁“马达”和“锚”室的严格分离，将凝聚素从一侧变成双向 DNA 环挤出。他们得出结论，SMC 反应循环中两个拓扑结合的 DNA 片段的方向决定了 DNA 环挤出的方向性。

据了解，SMC蛋白复合物通过挤出 DNA 环来构建基因组，但其活性的分子机制仍然未知。

附：英文原文

Title: A hold-and-feed mechanism drives directional DNA loop extrusion by condensin

Author: Indra A. Shaltiel, Sumanjit Datta, Léa Lecomte, Markus Hassler, Marc Kschonsak, Sol Bravo, Catherine Stober, Jenny Ormanns, Sebastian Eustermann, Christian H. Haering

Issue&Volume: 2022-06-03

Abstract: Structural maintenance of chromosomes (SMC) protein complexes structure genomes by extruding DNA loops, but the molecular mechanism that underlies their activity has remained unknown. We show that the active condensin complex entraps the bases of a DNA loop transiently in two separate chambers. Single-molecule imaging and cryo–electron microscopy suggest a putative power-stroke movement at the first chamber that feeds DNA into the SMC–kleisin ring upon adenosine triphosphate binding, whereas the second chamber holds on upstream of the same DNA double helix. Unlocking the strict separation of “motor” and “anchor” chambers turns condensin from a one-sided into a bidirectional DNA loop extruder. We conclude that the orientation of two topologically bound DNA segments during the SMC reaction cycle determines the directionality of DNA loop extrusion.

DOI: abm4012

Source: https://www.science.org/doi/10.1126/science.abm4012