Systematic Identification of Proteins Binding to Chromatin-Embedded Ubiquitylated H2B Reveals Recruitment of SWI/SNF to Regulate Transcription

• Affinity purification with H2Bub1 chromatin identifies more than 90 associated factors
• The NELF, DSIF, INT, and SWI/SNF complexes bind preferentially to H2Bub1 chromatin
• Gene-specific recruitment of SWI/SNF in vivo depends on H2Bub1
• SWI/SNF is required for optimal transcription of RNF20-dependent genes

SummaryChromatin posttranslational modifications (PTMs), including monoubiquitylation of histone H2B on lysine 120 (H2Bub1), play a major role in regulating genome functions. To elucidate the molecular mechanisms of H2Bub1 activity, a chromatin template uniformly containing H2Bub1 was used as an affinity matrix to identify preferentially interacting human proteins. Over 90 such factors were found, including proteins and protein complexes associated with transcription, RNA posttranscriptional modifications, and DNA replication and repair. Notably, we found that the SWI/SNF chromatin remodeling complex associates preferentially with H2Bub1-rich chromatin. Moreover, SWI/SNF is required for optimal transcription of a subset of genes that are selectively dependent on H2Bub1. Our findings substantially expand the known H2Bub1 interactome and provide insights into the functions of this PTM in mammalian gene regulation.

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