Cockayne syndrome B protein acts as an ATP-dependent processivity factor that helps RNA polymerase II overcome nucleosome barriers

Jun Xu, Wei Wang, Liang Xu, Jia-Yu Chen, Jenny Chong, Juntaek Oh, Andres E. Leschziner, Xiang-Dong Fu, Dong Wang
2020 Proceedings of the National Academy of Sciences of the United States of America  
While loss-of-function mutations in Cockayne syndrome group B protein (CSB) cause neurological diseases, this unique member of the SWI2/SNF2 family of chromatin remodelers has been broadly implicated in transcription elongation and transcription-coupled DNA damage repair, yet its mechanism remains largely elusive. Here, we use a reconstituted in vitro transcription system with purified polymerase II (Pol II) and Rad26, a yeast ortholog of CSB, to study the role of CSB in transcription
more » ... through nucleosome barriers. We show that CSB forms a stable complex with Pol II and acts as an ATP-dependent processivity factor that helps Pol II across a nucleosome barrier. This noncanonical mechanism is distinct from the canonical modes of chromatin remodelers that directly engage and remodel nucleosomes or transcription elongation factors that facilitate Pol II nucleosome bypass without hydrolyzing ATP. We propose a model where CSB facilitates gene expression by helping Pol II bypass chromatin obstacles while maintaining their structures.
doi:10.1073/pnas.2013379117 pmid:32989164 fatcat:in4uejoxd5htlipbjmszrtlzmi