Histone H3 and the Histone Acetyltransferase Hat1p Contribute to DNA Double-Strand Break Repair

Abstract

The modification of newly synthesized histones H3 and H4 by type B histone acetyltransferases has been proposed to play a role in the process of chromatin assembly. The type B histone acetyltransferase Hat1p and specific lysine residues in the histone H3 NH₂-terminal tail (primarily lysine 14) are redundantly required for telomeric silencing. As many gene products, including other factors involved in chromatin assembly, have been found to participate in both telomeric silencing and DNA damage repair, we tested whether mutations in HAT1 and the histone H3 tail were also sensitive to DNA-damaging agents. Indeed, mutations both in specific lysine residues in the histone H3 tail and in HAT1 resulted in sensitivity to methyl methanesulfonate. The DNA damage sensitivity of the histone H3 and HAT1 mutants was specific for DNA double-strand breaks, as these mutants were sensitive to the induction of an exogenous restriction endonuclease, EcoRI, but not to UV irradiation. While histone H3 mutations had minor effects on nonhomologous end joining, the primary defect in the histone H3 and HAT1 mutants was in the recombinational repair of DNA double-strand breaks. Epistasis analysis indicates that the histone H3 and HAT1 mutants may influence DNA double-strand break repair through Asf1p-dependent chromatin assembly.

We thank Tamara Kelly and Ericka Eugenie for help in the construction of strains and plasmids; R. Mann, M. Grunstein, and J. Rine for plasmids; and M. DuBois and D. Gottschling for generously providing yeast strains and plasmids prior to publication. We also thank A. Sklenar and M. DuBois and A. Annunziato for critical reading of the manuscript.

This work was supported by a seed grant from the American Cancer Society (Ohio Division), Research Project grant RPG-00-340-01-CSM from the American Cancer Society, and the National Institutes of Health (GM62970-01).