Interplay between chromatin modifying and remodeling complexes in transcriptional regulation.

The question of a possible functional relationship between different chromatin-altering enzymatic activities is of great interest. Several remarkable parallels have been revealed regarding the action of the remodeling complex SWI/SNF and the histone acetylation complex SAGA during transcriptional activation in S. cerevisiae. Many promoters, but not all, that require one complex require the other as well. Mutations that disrupt both complexes cause much more severe phenotypes than single mutations. Both types of complexes are recruited to specific promoters by interaction with DNA-bound acidic activators, resulting in targeted acetylation and transcriptional activation. Taken together the data argue for independent mechanisms, but similar recruitment and functional interplay between these two types of chromatin-altering activities.