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. Author manuscript; available in PMC: 2017 Jul 26.
Published in final edited form as: ACS Nano. 2016 Jul 6;10(7):7073–7084. doi: 10.1021/acsnano.6b03218

Figure 7. Model of Gal4-VP16 binding to a nucleosome integrated into a nanocaliper.

Figure 7

Our nanocaliper studies of the 6L nucleosome indicate that in the presence of Gal4-VP16 there are three possible states. (State I) The nucleosome without Gal4-VP16 bound is unwrapped ~20 bp by the nanocaliper with an end-to-end distance of 23 nm. (State II) The nucleosome is unwrapped by a little more than 20 bp so Gal4-VP16 can bind and the end-to-end distance increases to 26 nm. In this state, the DNA still wraps about 1 full turn around the histone octamer. (State III) While Gal4-VP16 is bound to the nucleosome, the nucleosome reorients so that it is almost completely unwrapped. This significantly increases the end-to-end distance of the nucleosome to 45 nm.