Fig 6.

Schematic diagram of a genetic pathway for H3K56 acetylation and histone chaperones CAF-1 and HIR in epigenetic switching. H3K56 acetylation is controlled by the histone acetyltransferase Rtt109 and deacetylated by the NAD-dependent histone deacetylase Hst3. CAF-1 and HIR mediate nucleosome assembly functions downstream of Rtt109. This pathway is responsive to genotoxins and nicotinamide through inhibition of Hst3 (37) and functions in parallel to GlcNAc, which activates Wor1. Hst3 is known to actively remove H3K56 acetylation marks during chromatin maturation, whereas Rtt109 activity is on free histones before deposition (39, 40, 57, 58). Line thickness indicates relative nucleosome turnover dynamics.