UCSF

The promoters of genes have a stereotypical chromatin architecture

characterized by a nucleosome-free region (NFR), which contain DNA motifs that

are involved in gene transcription. Additionally, at least one of the nucleosomes

flanking a NFR tends to contain the histone H2A variant H2A.Z. The

mechanisms behind NFR formation and H2A.Z deposition have not been well

characterized. This dissertation encompasses approaches towards an

understanding of these mechanisms. A specific sequence of DNA isolated from

a yeast promoter was shown to be sufficient to program NFR formation and

H2A.Z deposition. The remodeling activity of this sequence of DNA required the

activities of the transcription factor Reb1 and chromatin remodeling complex

RSC. The involvement of Reb1, RSC, and another transcription factor, Abf1, in

nucleosome positioning at other gene promoters was assayed, and RSC was

determined to play a significant role in the proper positioning of nucleosomes at

promoters. Lastly, because H2A.Z deposition is not required for general NFR

formation, the hypothesis that H2A.Z deposition requires prior NFR formation

was tested.