Cohesin facilitates nucleosome invasion by transcription factors.

Authors

Shane Stoeber, Hengye Chen, Ruo-Wen Chen, Courtney Smith, Sam Becker, Sarah Vinson, Michael G Poirier, Lu Bai

Published in

Science advances. Volume 12. Issue 32. Pages eaef1603. Aug 07, 2026. Epub Aug 05, 2026.

Abstract

Nucleosomes present a major barrier to transcription factor (TF) binding. However, a subgroup of TFs known as pioneer factors (PFs) can recognize motifs covered by nucleosomes and initiate chromatin opening. PFs also bind nucleosomal substrates with high affinity in vitro, which may facilitate their nucleosome invasion in vivo. Here, we show that LexA, a bacterial TF with poor nucleosome binding in vitro, can rapidly invade into a well-positioned nucleosome from a motif positioned at the dyad when expressed ectopically in yeast. This notable contrast between LexA binding in vitro and in vivo raises the possibility that TFs can exploit nucleosome dynamics in vivo to access occluded sites. Unexpectedly, we find that LexA-mediated chromatin opening can occur in the absence of DNA replication, chromatin remodeling, histone turnover, and a few histone chaperones. Instead, nucleosome invasion by LexA and a native PF, Cbf1, is promoted by the cohesin complex, illustrating an intriguing connection between cohesin and TF binding. Together, our results demonstrate that even nonpioneer TFs like LexA can bind and displace nucleosomes in vivo, through a process facilitated by cohesin.

PMID:
42555726
Bibliographic data and abstract were imported from PubMed on 06 Aug 2026.

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