Fig. 4.

Histone tracking during transcription. (A) Schematic of the experimental design. Before the experiment, cells were grown without reaching saturation for at least 8 doublings in YP + raffinose. In raffinose, the GAL10 promoter drives low basal transcription. In dextrose, the locus is repressed by Gal80, and in the presence of galactose, transcription is induced 1,000-fold by Gal4. (B) Biotinylated histones did not move locally during transcription; however, biotinylated nucleosome density decreased during transcription (rel. background biotinylation) reflecting removal of nucleosomes during transcription. TetR-BirA (anti-V5) showed ChIP density in induced samples, which reflects a previously characterized ChIP artifact in which highly transcribed genes are enriched in chromatin pulldown fractions (26, 27). The results plotted are representative of 2 biological replicates. (C) Transcription from the gal10::TetO locus was induced >1,000-fold by addition of galactose.