Figure 7. TALEs facilitate displacement of a positioned nucleosome on the IL-2 promoter.

(A) Proposed TALE mechanism upon binding to the IL-2 promoter (not drawn to scale). Top panel is an illustration of the proposed chromatin structure of the IL-2 promoter in the absence of TALE activators. The approximate location of response elements adapted from previously published data [31]. Circle represents a positioned nucleosome located approximately 60 to 200 bp upstream of the TSS [31]. Boxed enclosed ‘T’ represents the TATA box. Bottom panel indicates location of TALE activators relative to TSS and proposed mechanism of action on the IL-2 promoter. IL-2 specific primers were used to probe various regions across the IL-2 promoter. Arrows indicate the approximate location of each region amplified by their corresponding primer set. All TALE activators were fused to VP64 (activation domain colored green) with the exception of IL2D’, which was fused to TBP (activation domain colored red). (B) Results of chromatin analysis using CHART-PCR. Percent accessibility was calculated as described in Methods and plotted for both empty vector control (black bars) and TALE activators (shaded bars). GAPDH used as internal control to monitor DNase I digestion. Results shown are of three independent experiments (error bars, mean +/− SD, n = 3). Statistical analysis was determined using one tailed, Welch’s t-test (P<0.05 *).