Figure 7. Schematic of the interplay between transcriptional bursting, nucleosomes, and TF dynamics.

1. In full induction conditions (high galactose), bursting of the GAL genes is determined by the binding dynamics of Gal4. A longer Gal4 dwell time results in a larger burst size. The Gal4 dwell time is determined by the affinity of the UAS and is significantly reduced by fragile nucleosomes.
2. In lower galactose concentration, Gal80 represses Gal4 activity and transcription initiation during some bursts, resulting in a lower burst frequency. When Gal4 is not repressed, the burst duration is similar to full induction conditions. We propose that galactose concentration determines the availability of active Gal4.
3. In inactive conditions, Gal4 still binds DNA, but is fully repressed by Gal80.