Fig. 1.

Removal of H3/H4 is the rate-limiting step during chromatin disassembly. (A) Schematic of the PHO5 promoter region. Lighter circles represent nucleosomes that are disassembled upon transcriptional activation. The bar indicates the region amplified in the ChIP analyses. (B) Asf1 is required for the normal kinetics of PHO5 activation. Acid phosphatase levels were measured in strains JLY096 (WT) and SKW043 (asf1Δ) at the indicated times after transfer to low-phosphate media. (C and D) Histone H3 and H2B-HA levels over the PHO5 promoter relative to the GAL1 control region in WT yeast (C) and in asf1Δ yeast (D), from the same time course as in B.