美国德克萨斯大学西南医学中心Hongtao Yu、得克萨斯大学奥斯汀分校Ilya J. Finkelstein等研究人员合作发现，人类黏连蛋白（cohesin）通过环挤压来压缩DNA。这一研究成果于2019年11月28日在线发表在国际学术期刊《科学》上。

研究人员使用单分子成像发现重组人黏连蛋白-NIPBL复合物通过挤压DNA环来压实裸露的和核小体结合的DNA。黏连蛋白压缩DNA需要ATP水解，并且是力敏感的。

这种压缩过程以每秒0.5千碱基的平均速率工作于数十千碱基上。双链DNA的压缩表明黏连蛋白二聚体双向挤压DNA环。这些结果表明，黏连蛋白-NIPBL是能够进行环挤出的ATP驱动分子机器。

据悉，黏连蛋白是一种染色体结合的多亚基ATP酶复合物。粘连蛋白加载到染色体后，会生成染色体环以调节染色体功能。有人提出粘着蛋白通过环挤压组织基因组，但缺乏直接的证据。

附：英文原文

Title: Human cohesin compacts DNA by loop extrusion

Author: Yoori Kim, Zhubing Shi, Hongshan Zhang, Ilya J. Finkelstein, Hongtao Yu

Issue&Volume: 2020/11/28

Abstract: AbstractCohesin is a chromosome-bound multisubunit ATPase complex. Following its loading onto chromosomes, cohesin generates chromosome loops to regulate chromosome functions. It has been suggested that cohesin organizes the genome via loop extrusion, but direct evidence is lacking. Here, we use single-molecule imaging to show that recombinant human cohesin-NIPBL complex compacts both naked and nucleosome-bound DNA by extruding DNA loops. DNA compaction by cohesin requires ATP hydrolysis, and is force-sensitive. This compaction is processive over tens of kilobases (kb) at an average rate of 0.5 kb per second. Compaction of double-tethered DNA suggests that a cohesin dimer extrudes DNA loops bidirectionally. Our results establish cohesin-NIPBL as an ATP-driven molecular machine capable of loop extrusion.

DOI: 10.1126/science.aaz4475

Source: https://science.sciencemag.org/content/early/2019/11/25/science.aaz4475