Fig. 4: Structural analysis of SADS₃.

a Schematic diagram showing six representative AsLOV2 dimer conformation candidates and the corresponding residuals between SADS₃ and the best-fit scattering curve determined from the structural analysis. In the upper panel, the results of structural analysis for three hetero L/G dimers are shown, and in the lower panel, those for three homo L/L dimers are shown. In the schematic of the frames for the homo- and hetero- dimers, the light state LOV2 core ___domain (L) is depicted in bright yellow, and the non-activated LOV2 core ___domain (G) is depicted in dark yellow. Jα helix is shown in blue, and A’α is shown in red. The best-fit curve with the smallest residual and χ² value is highlighted with the red box. The docking score (DS) and confidence score (CS) from molecular docking simulations, which assess the plausibility of dimer formation, are shown for each conformation. b Comparison of SADS₃ (black), static difference scattering curves (qΔS_static, light state − dark state, gray), and the best-fit curve of the optimal structure of P (red). c Comparison of low-resolution structures reconstructed from static SAXS and the optimal structure of P obtained from TRXL. d Representation of helices and residues associated with dimerization in representative protein conformations for P. Jα and A’α are shown in blue and red, and, K413 (yellow) and E475 (green) which form a salt bridge are represented as spheres. e Dimer fractions obtained from SEC for WT (black), C450A (light gray), K413E (orange), E475K (green), ΔJα (blue), ΔA’α (red), and ΔJα/ΔA’α (brown). The SEC results for each construct in the dark state are represented as triangles, while those in the light state are represented as circles.