Figure 42.

Intrinsically disordered dFACT protein and effect of phosphorylation on the structure visualized by HS-AFM. (a,b) Clips of successive HS-AFM images of phosphorylated dFACT-WT (a) and dephosphorylated dFACT-10SA (b). Imaging rate, ∼14 fps; scan area, 100 × 100 nm² with 80 × 80 pixels; Z-scale, 4.0 nm. The observed molecular features of dFACT are schematized according to the definitions in (c). These schematics were drawn freehand by tracing the AFM images by visual estimation. (c) Schematics representing the characteristics of dFACT observed by HS-AFM (upper schematic) and its side-view (lower schematic). Gray-colored ellipses and black-colored thick solid lines represent the globular domains (GD) and the intrinsically disordered regions, respectively. (d) Histograms of distance D_1–2 indicated in (c) measured for dFACT-WT (upper) and dFACT-10SA (bottom). (e) Histograms of height H₂ indicated in (c) measured for dFACT-WT (upper) and dFACT-10SA (bottom). The histograms appear to have two peaks at 1.6–1.7 and ∼1.1 nm, which correspond to HMG associated with an IDR and HMG alone, respectively.