INO80 and SWR complexes: relating structure to function in chromatin remodeling

• INO80-C and SWR-C remodelers bind to nucleosomal substrates in very distinct ways.
• Modules within SWR-C/INO80-C enable cooperative and conditional chromatin binding.
• Subcomplexes within SWR-C and INO80-C may dissociate and function independently.

Virtually all DNA-dependent processes require selective and controlled access to the DNA sequence. Governing this access are sophisticated molecular machines, nucleosome remodelers, which regulate the composition and structure of chromatin, allowing conversion from open to closed states. In most cases these multisubunit remodelers operate in concert to organize chromatin structure by depositing, moving, evicting, or selectively altering nucleosomes in an ATP-dependent manner. Despite sharing a conserved domain architecture, chromatin remodelers differ significantly in how they bind to their nucleosomal substrates. Recent structural studies link specific interactions between nucleosomes and remodelers to the diverse tasks they carry out. We review here insights into the modular organization of the INO80 family of nucleosome remodelers. Understanding their structural diversity will help to shed light on how these related ATPases modify their nucleosomal substrates.