Histone modification governs the cell cycle regulation of a replication-independent chromatin assembly pathway in Saccharomyces cerevisiae

We describe a replication-independent, cell cycle-regulated chromatin assembly pathway in budding yeast. The activity of this pathway is low in S phase extracts but is very high in G(2), M, and G(1) cell extracts, with peak activity in late M/early G(1). The cell cycle regulation of this pathway requires a specific pattern of posttranslational modification of histones H3 and/or H4, which is distinct for H3/H4 present in S phase versus M and G(1) phase cell extracts. Histone H3/H4 modification is therefore important for the reciprocal control of replication-dependent and -independent chromatin assembly pathways during the cell cycle.