Figure 4

Global structural analysis by SEC-SAXS-MALS. (A) Top: SEC-MALS-SAXS chromatograms for apo-CCP2 dimer (5 mg/mL, apo1), apo-CCP2 tetramer (10 mg/mL, apo2), holo-CCP2 (5 mg/mL holo). Solid lines represent the UV 280 nm (light blue) or integrated SAXS signal (dark blue) in arbitrary units, while symbols represent molecular mass (cyan) and Rg values for each collected SAXS frame (dark blue) versus elution time. (B,C) p(r) functions calculated for the experimental data (black) of apo-CCP2 dimer, trimer, and, tetramer; and holo-CCP2 dimer and tetramer, shown in Figure S4. The area of the p(r) is normalized relative to the MW estimated by SAXS⁴⁸ and is listed in Table S1. Theoretical p(r) function is calculated from the theoretical SAXS curves shown in Figure S4 of the corresponding models shown in (D,E). (D) Comparison of the experimental p(r) functions of holo-CCP2 dimer (blue) and apo-CCP2 dimer (red) together with the derived 3D structural models (see Materials and methods). C-terminal region (C-term) is highlighted. (E) Comparison of the experimental p(r) functions of holo-CCP2 tetramer (magenta) and apo-CCP2 dimer (green) together with the derived 3D structural models (see Materials and methods). The position of the conserved cysteine is highlighted in yellow.