Structures at (a) pH8.0, (b) pH6.5, (c) pH5.0, determined to 4.0, 4.4 and 12 Å resolution, respectively. Left panels show the surface of the cryoEM maps. Densities corresponding to the E protein layer and Fabs are coloured in yellow and magenta, respectively. Black triangle indicates an asymmetric unit and the 5-, 3-, 2-fold vertices are labelled. Right panels show zoom-in views of the fitted molecules into the density maps. (a, right panel) The 4.0 Å resolution pH8.0 complex show well-resolved bulky side chain densities (grey mesh). The Cα backbone, the nitrogen and oxygen atoms are coloured in green, blue and red, respectively. (b, right panel) The 4.4 Å resolution pH6.5 complex map showed density (grey transparent surface) separation between the β strands. DII of E protein is coloured in yellow. (c, right panel) Densities of the 12 Å resolution pH5.0 complex showed clear borders and shapes corresponding to the Fab C10-E protein dimeric structures. The variable region of the Fab molecule, DI, DII and DIII of the E protein are coloured in green, red, yellow and blue, respectively.