Stoichiometry of Rtt109 complexes with Vps75 and histones H3-H4.

Histone acetylation is one of many posttranslational modifications that affect nucleosome accessibility. Vps75 is a histone chaperone that stimulates Rtt109 acetyltransferase activity toward histones H3-H4 in yeast. In this study, we use sedimentation velocity and light scattering to characterize various Vps75-Rtt109 complexes, both with and without H3-H4.

Two factor authentication: Asf1 mediates crosstalk between H3 K14 and K56 acetylation.

The ability of histone chaperone Anti-silencing factor 1 (Asf1) to direct acetylation of lysine 56 of histone H3 (H3K56ac) represents an important regulatory step in genome replication and DNA repair. In Saccharomyces cerevisiae, Asf1 interacts functionally with a second chaperone, Vps75, and the lysine acetyltransferase (KAT) Rtt109. Both Asf1 and Vps75 can increase the specificity of histone acetylation by Rtt109, but neither alter selectivity.

Histone Chaperone Nap1 Is a Major Regulator of Histone H2A-H2B Dynamics at the Inducible GAL Locus.

Histone chaperones, like nucleosome assembly protein 1 (Nap1), play a critical role in the maintenance of chromatin architecture. Here, we use the GAL locus in Saccharomyces cerevisiae to investigate the influence of Nap1 on chromatin structure and histone dynamics during distinct transcriptional states. When the GAL locus is not expressed, cells lacking Nap1 show an accumulation of histone H2A-H2B but not histone H3-H4 at this locus.