Polybromo-1-bromodomains bind histone H3 at specific acetyl-lysine positions

Biochem Biophys Res Commun. 2007 Apr 13;355(3):661-6. doi: 10.1016/j.bbrc.2007.01.193. Epub 2007 Feb 9.

Abstract

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.

MeSH terms

  • Acetylation
  • Amino Acid Sequence
  • DNA-Binding Proteins
  • Histones / chemistry*
  • Histones / metabolism
  • Humans
  • Lysine / metabolism*
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • RNA Cap-Binding Proteins / metabolism
  • Transcription Factors / chemistry*
  • Transcription Factors / metabolism

Substances

  • DNA-Binding Proteins
  • Histones
  • Nuclear Proteins
  • PBRM1 protein, human
  • RNA Cap-Binding Proteins
  • Transcription Factors
  • Lysine