The Swi2/Snf2 bromodomain is required for the displacement of SAGA and the octamer transfer of SAGA-acetylated nucleosomes.
The SWI/SNF and SAGA chromatin-modifying complexes contain bromodomains that help anchor these complexes to acetylated promoter nucleosomes. To study the importance of bromodomains in these complexes, we have compared the chromatin-remodeling and octamer-transfer activity of the SWI/SNF complex to a mutant complex that lacks the Swi2/Snf2 bromodomain. Here we show that the SWI/SNF complex can remodel or transfer SAGA-acetylated nucleosomes more efficiently than the Swi2/Snf2 bromodomain-deleted complex. These results demonstrate that the Swi2/Snf2 bromodomain is important for the remodeling as well as for the octamer-transfer activity of the complex on H3-acetylated nucleosomes. Moreover, we show that, although the wild-type SWI/SNF complex displaces SAGA that is bound to acetylated nucleosomes, the bromodomain mutant SWI/SNF complex is less efficient in SAGA displacement. Thus, the Swi2/Snf2 bromodomain is required for the full functional activity of SWI/SNF on acetylated nucleosomes and is important for the displacement of SAGA from acetylated promoter nucleosomes.
Hassan
Ahmed H
AH
Faculty of Medicine and Health Sciences, Department of Biochemistry, United Arab Emirates University, P. O. Box 17666, Al-Ain, United Arab Emirates. ahmedh@uaeu.ac.ae
Awad
Salma
S
Prochasson
Philippe
P
D000107:Acetylation; D000251:Adenosine Triphosphatases; D002843:Chromatin / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D009707:Nucleosomes / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
D002843:Chromatin; D004268:DNA-Binding Proteins; D009707:Nucleosomes; C507785:SAGA complex, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae