FIG. 2.
Nucleosome displacement suppresses the SAGA acetylation peak. (A) Scanning in vitro ChIP assay, with the relative positions of the probes for the pG5E4T array indicated. The array was subjected to nucleosome displacement and ChIP as described in Fig. 1B. The membrane was hybridized to a series of labeled probes shown in the diagram. The positions of the probes relative to the HindIII restriction enzyme site are also indicated on the diagram. The blots are shown below each corresponding probe. (B) The SAGA acetylation peak is suppressed by SWI/SNF. The %IP was normalized to the %IP at the −A probe, which is upstream of the Gal4 binding sites and the E4 promoter. The solid line depicts the H3 acetylation profile along the template, while the dashed line corresponds to the effect of SWI/SNF nucleosome displacement on the H3 acetylation profile. A Student t test was used to determine the statistical significance of the difference in the acetylation profile before and after SWI/SNF treatment. The P values for the t test are given below each segment of the array.