Human SMARCA5 is continuously required to maintain nucleosome spacing

Genetic models suggested that SMARCA5 was required for DNA-templated events including transcription, DNA replication, and DNA repair. We engineered a degron tag into the endogenous alleles of SMARCA5, a catalytic component of the imitation switch complexes in three different human cell lines to define the effects of rapid degradation of this key regulator. Degradation of SMARCA5 was associated with a rapid increase in global nucleosome repeat length, which may allow greater chromatin compaction. However, there were few changes in nascent transcription within the first 6 h of degradation. Nevertheless, we demonstrated a requirement for SMARCA5 to control nucleosome repeat length at G1/S and during the S phase. SMARCA5 co-localized with CTCF and H2A.Z, and we found a rapid loss of CTCF DNA binding and disruption of nucleosomal phasing around CTCF binding sites. This spatiotemporal analysis indicates that SMARCA5 is continuously required for maintaining nucleosomal spacing. [Display omitted] •Target-specific protein degradation of endogenous human SMARCA5•Degradation of SMARCA5 leads to a rapid loss in CTCF DNA binding•SMARCA5 regulates nucleosome repeat length independent of the cell cycle•CTCF and SMARCA5 co-localize at H2A.Z-containing sites Bomber et al. utilize degron tagging of the endogenous human chromatin-remodeling enzyme SMARCA5, coupled with a multi-omics approach, to define the requirements for SMARCA5-mediated nucleosome sliding. SMARCA5 co-localized with H2A.Z and CTCF and was required for CTCF DNA binding, nucleosomal phasing at these sites, and maintaining nucleosome repeat length.