Fig. 5. Overall structural effect of illumination on OCP structure.

Datasets from which all images are derived (Dark, I1–I4) have a resolution of 1.3–1.4 Å (Supplementary Table 1) and time points at which crystals were cryo-trapped are indicated for I1–I4. Each structure is coloured in cyan-yellow gradient based on B-factor (10.0 (cyan)-30.0 (yellow)). (I1- I4, upper panel) F₀ – F₀ Difference electron density (DED) maps (blue/red at ±3.5σ) for the four states are shown below each corresponding structure: (I1) 1 min (F_I1 – F_Dark), (I2) 2 min (F_I2 – F_Dark), (I3) 5 min (F_I3 – F_Dark) and (I4) 10 min (F_I4 – F_Dark). The DED signals are localized in the three major areas: zone 1: NTD; zone 2: NTE; zone 3: alpha-helices in CTD. Note that some DED signals are observed at the interface between the two domains (red arrows in I1 and I2), while the C-terminal tail (CTT) does not exhibit any noticeable DED signal. Red: negative DED, blue: positive DED on the −3.5σ/3.5σ contour levels, respectively. See main text for further explanation. (I1–I4, lower panel) DED signals are also shown as integrated signals⁵³ around each atom in the protein chain. The figure was created using PyMOL Molecular Graphics System (Version 2.5.0).