Polybromo-1-bromodomains bind histone H3 at specific acetyl-lysine positions.
The human polybromo-1 protein is thought to localize the Polybromo, BRG1-associated factors chromatin-remodeling complex to kinetochores during mitosis via direct interaction of its six tandem bromodomains with acetylated nucleosomes. Bromodomains are acetyl-lysine binding modules roughly 100 amino acids in length originally found in chromatin associated proteins. Previous studies verified acetyl-histone binding by each bromodomain, but site-specificity, a central tenet of the histone code hypothesis, was not examined. Here, the acetylation site-dependence of bromodomain-histone interactions was examined using steady-state fluorescence anisotropy. Results indicate that single bromodomains bind specific acetyl-lysine sites within the histone tail with sub-micromolar affinity. Identification of duplicate target sites suggests that native Pb1 interacts with both copies of histone H3 upon nucleosome assembly. Quantitative analysis of single bromodomain-histone interactions can be used to develop hypotheses regarding the histone acetylation pattern that acts as the binding target of the native polybromo-1 protein.
Chandrasekaran
Renu
R
Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA.
Thompson
Martin
M
D000107:Acetylation; D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins; D006657:Histones / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D039381:RNA Cap-Binding Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; C102195:PBRM1 protein, human; D039381:RNA Cap-Binding Proteins; D014157:Transcription Factors; D008239:Lysine