Figure 7.

Models of HAT module and TF binding to a partially unwrapped nucleosome. Model 1: Gal4–VP16 first binds to its recognition sequence and then recruits the HAT module. Model 2: Gal4–VP16 and the HAT module interact with each other before binding the nucleosome together. Model 3: the HAT module interacts with the nucleosome first, allowing Gal4–VP16 to bind at a higher affinity. Since the impact of the HAT module on TF binding does not depend on the HAT acetylation activities, acetylation is not indicated in the model. However, histone acetylation will occur when the HAT module is bound to the nucleosome, which includes the fully bound nucleosome and the intermediate state of Model 3.