Expansion of the ISWI chromatin remodeler family with new active complexes

ISWI chromatin remodelers mobilize nucleosomes to control DNA accessibility. Complexes isolated to date pair one of six regulatory subunits with one of two highly similar ATPases. However, we find that each endogenously expressed ATPase co-purifies with every regulatory subunit, substantially increasing the diversity of ISWI complexes, and we additionally identify BAZ2B as a novel, seventh regulatory subunit. Through reconstitution of catalytically active human ISWI complexes, we demonstrate that the new interactions described here are stable and direct. Finally, we profile the nucleosome remodeling functions of the now expanded family of ISWI chromatin remodelers. By revealing the combinatorial nature of ISWI complexes, we provide a basis for better understanding ISWI function in normal settings and disease.