小组确定Pol II单独产生的扭矩为9 pN·nm，与TFIIS一起产生的扭矩为13 pN·nm，使其成为强大的旋转电机。当Pol II遇到核小体时，在染色质底物上的传代比在单核小体底物上的传代更有效，这表明染色质在转录过程中显著缓冲了扭转应力。
此外，拓扑异构酶的超卷曲松弛允许Pol II通过多个核小体转录。他们的研究结果揭示了染色质的作用，而不是传统的认为它是转录的障碍。
据介绍，在真核生物转录过程中，Pol II会克服核小体障碍，并且由于DNA的螺旋结构，它们也会相对于DNA旋转，产生扭转应力。然而，人们对Pol II如何通过核小体转录而超缠绕DNA的理解有限。
附：英文原文
Title: Chromatin buffers torsional stress during transcription
Author: Jin Qian, Lucyna Lubkowska, Shuming Zhang, Chuang Tan, Yifeng Hong, Xiaomeng Jia, Robert M. Fulbright, James T. Inman, Taryn M. Kay, Joshua Jeong, Glenn Hauk, Deanna Gotte, James M. Berger, Mikhail Kashlev, Michelle D. Wang
Issue&Volume: 2025-12-18
Abstract: During eukaryotic transcription, Pol II must overcome nucleosome obstacles and, because of DNA’s helical structure, must also rotate relative to DNA, generating torsional stress. However, there is limited understanding of how Pol II transcribes through nucleosomes while supercoiling DNA. Here, we determined that Pol II generates a torque of 9 pN·nm alone and 13 pN·nm with TFIIS, making it a powerful rotary motor. When Pol II encounters a nucleosome, passage becomes more efficient on a chromatin substrate than on a single-nucleosome substrate, demonstrating that chromatin significantly buffers torsional stress during transcription. Furthermore, topoisomerase supercoiling relaxation allows Pol II to transcribe through multiple nucleosomes. Our results reveal a role of chromatin beyond the more conventional view of it being just a roadblock to transcription.
DOI: adv0134
Source: https://www.science.org/doi/10.1126/science.adv0134