Specific Acetylation Patterns of H2A.Z Form Transient Interactions with the BPTF Bromodomain

Biochemistry. 2017 Sep 5;56(35):4607-4615. doi: 10.1021/acs.biochem.7b00648. Epub 2017 Aug 23.

Abstract

Post-translational lysine acetylation of histone tails affects both chromatin accessibility and recruitment of multifunctional bromodomain-containing proteins for modulating transcription. The bromodomain- and PHD finger-containing transcription factor (BPTF) regulates transcription but has also been implicated in high gene expression levels in a variety of cancers. In this report, the histone variant H2A.Z, which replaces H2A in chromatin, is evaluated for its affinity for BPTF with a specific recognition pattern of acetylated lysine residues of the N-terminal tail region. Although BPTF immunoprecipitates H2A.Z-containing nucleosomes, a direct interaction with its bromodomain has not been reported. Using protein-observed fluorine nuclear magnetic resonance (PrOF NMR) spectroscopy, we identified a diacetylation of H2A.Z on lysine residues 4 and 11, with the highest affinity for BPTF with a Kd of 780 μM. A combination of subsequent 1H NMR Carr-Purcell-Meiboom-Gill experiments and photo-cross-linking further confirmed the specificity of the diacetylation pattern at lysines 4 and 11. Because of an adjacent PHD domain, this transient interaction may contribute to a higher-affinity bivalent interaction. Further evaluation of specificity toward a set of bromodomains, including two BET bromodomains (Brd4 and BrdT) and two Plasmodium falciparum bromodomains, resulted in one midmicromolar affinity binder, PfGCN5 (Kd = 650 μM). With these biochemical experiments, we have identified a direct interaction of histone H2A.Z with bromodomains with a specific acetylation pattern that further supports the role of H2A.Z in epigenetic regulation.

MeSH terms

  • Acetylation
  • Amino Acid Sequence
  • Binding Sites
  • Escherichia coli
  • Gene Expression Regulation / physiology
  • Histones / genetics
  • Histones / metabolism*
  • Ligands
  • Models, Molecular
  • Plasmodium falciparum
  • Protein Conformation
  • Protein Domains

Substances

  • Histones
  • Ligands
  • histone H2A.F-Z