Regulation of NuA4 Histone Acetyltransferase Activity in Transcription and DNA Repair by Phosphorylation of Histone H4

Abstract

The NuA4 complex is a histone H4/H2A acetyltransferase involved in transcription and DNA repair. While histone acetylation is important in many processes, it has become increasingly clear that additional histone modifications also play a crucial interrelated role. To understand how NuA4 action is regulated, we tested various H4 tail peptides harboring known modifications in HAT assays. While dimethylation at arginine 3 (R3M) had little effect on NuA4 activity, phosphorylation of serine 1 (S1P) strongly decreased the ability of the complex to acetylate H4 peptides. However, R3M in combination with S1P alleviates the repression of NuA4 activity. Chromatin from cells treated with DNA damage-inducing agents shows an increase in phosphorylation of serine 1 and a concomitant decrease in H4 acetylation. We found that casein kinase 2 phosphorylates histone H4 and associates with the Rpd3 deacetylase complex, demonstrating a physical connection between phosphorylation of serine 1 and unacetylated H4 tails. Chromatin immunoprecipitation experiments also link local phosphorylation of H4 with its deacetylation, during both transcription and DNA repair. Time course chromatin immunoprecipitation data support a model in which histone H4 phosphorylation occurs after NuA4 action during double-strand break repair at the step of chromatin restoration and deacetylation. These findings demonstrate that H4 phospho-serine 1 regulates chromatin acetylation by the NuA4 complex and that this process is important for normal gene expression and DNA repair.

ACKNOWLEDGMENTS

We are indebted to C. D. Allis for providing anti-H4 P-Ser1 antibodies and the peptides with dual modifications. We are also grateful to Jessica Downs and Steve Jackson for anti-H2A P-Ser129, Patrick Grant and Jerry Workman for the peptides with a single available lysine, Luc Gaudreau for recombinant yeast histone H4, and Jim Haber for the JKM179 strain. We also thank D. Allis, S. Cheung, F. Turner, and C. Peterson for sharing results before publication and for encouragement.

This work was supported by a grant from the Canadian Institutes of Health Research (CIHR). R.T.U. was a CIHR postdoctoral fellow. O.J.-R. holds a CIHR/Canada Graduate Scholarship, and J.C. is a CIHR Investigator.