Chromatin buffers torsional stress during transcription
Summary
During eukaryotic transcription, RNA polymerase II (Pol II) must overcome nucleosome obstacles and, because of DNA's helical structure, must also rotate relative to DNA, which generates torsional stress. However, there is limited understanding of how Pol II transcribes through nucleosomes while supercoiling DNA. In this work, we determined that Pol II generates a torque of 9 piconewton-nanometers (pN·nm) alone and 13 pN·nm with transcription factor IIS (TFIIS), making it a powerful rotary
Content
# Chromatin buffers torsional stress during transcription
*Published: 2026 Mar 26*
During eukaryotic transcription, RNA polymerase II (Pol II) must overcome
nucleosome obstacles and, because of DNA's helical structure, must also rotate
relative to DNA, which generates torsional stress. However, there is limited
understanding of how Pol II transcribes through nucleosomes while supercoiling
DNA. In this work, we determined that Pol II generates a torque of 9
piconewton-nanometers (pN·nm) alone and 13 pN·nm with transcription factor IIS
(TFIIS), making it a powerful rotary motor. When Pol II encounters a nucleosome,
passage becomes more efficient on a chromatin substrate compared with on a
single-nucleosome substrate, which demonstrates that chromatin substantially
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: 10.1126/science.adv0134