A SWI/SNF-specific Ig-like domain, SWIFT, is a transcription factor binding platform

Mammalian SWI/SNF (BAF) chromatin remodeling complexes modulate DNA accessibility and gene expression, however, their genomic targeting mechanisms remain incompletely understood. Here, we identify SWIFT (SWI/SNF Ig-Fold for Transcription Factor Interactions), a conserved, broad transcription factor (TF) binding platform on the SMARCD subunits. SWIFT is necessary and sufficient for direct engagement with the transactivation domain of PU.1, a single mutation in which disrupts PU.1-mSWI/SNF binding, impairs complex targeting, and attenuates oncogenic transcription and proliferation in PU.1-dependent cancer cells. Dominant expression of the SWIFT domain in isolation sequesters TFs from mSWI/SNF and poisons TF-addicted cancer cells. Finally, TFs across diverse families interact with SMARCD paralog-specific SWIFT domains. These results define a major mechanism of cell type- and disease-specific mSWI/SNF chromatin targeting and inform approaches toward therapeutic modulation.