Mediator-nucleosome interaction

Mediator, a multiprotein complex involved in the regulation of RNA polymera se II transcription, binds to nucleosomes and acetylates histones. Three li nes of evidence identify the Nut1 subunit of Mediator as responsible for th e histone acetyltransferase (HAT) activity. An "in-gel" HAT assay reveals a single band of the appropriate size. Sequence alignment shows significant similarity of Nut1 to the GCN5-related N-acetyltransferase superfamily. Fin ally, recombinant Nut1 exhibits HAT activity in an in-gel assay.