Figure 5: PHF1 Tudor binding to the H3KC36me3-NCP stabilizes a more open form of the nucleosome.
From: Binding of PHF1 Tudor to H3K36me3 enhances nucleosome accessibility
FRET measurements of the influence of PHF1 Tudor on TF binding. (a) Diagram of the 601L DNA molecule. (b) A two-state model of TF binding to its target site within the nucleosome. (c) Crystal structure of the NCP (PDB ID: 1KX5) that indicates the positions of H3 (orange); MLA at H3K36C (dark red); Cy5 at H2AK119C (purple); Cy3 at the 5′ end of 601L (green); and the LexA target site (cyan). (d) Fluorescence spectra with Cy3–Cy5-labelled H3KC36me3-NCPs with 3 μM of LexA and either 0 μM (black), 10 μM (red) and 600 μM (purple) of PHF1 Tudor. The Cy3 emission increases as the Cy5 emission decreases indicating a decrease in FRET efficiency. (e) FRET efficiencies of LexA titrations with H3KC36me3 (black) and unmodified wild-type nucleosomes (red). FRET efficiencies were done in duplicate and fit to a non-cooperative binding curve with S1/2 of 3,000±600 nM and 2,400±900 nM for H3KC36me3 and unmodified wild-type nucleosomes, respectively. (f,g) FRET efficiencies of PHF1 Tudor titrations with (f) and without (g) 3 μM LexA and either H3KC36me3 (black) or unmodified NCPs (red). Error bars represent a standard deviation based on three experiments (PHF1 titrations) or two experiments (LexA titrations).
