Fig. 2

Overall Structure of the USUV-E protein. a An overview of the solved structure. The three domains (DI, DII, and DIII) are colored in red, yellow, and blue, respectively, and the fusion loop is in green. The inter-domain angles between DI and DII and between DI and DIII, which are calculated to be 144.4° and 153.6°, respectively, are highlighted. All the secondary structure elements (followed the nomenclature reported for ZIKV envelope [13]) referred to in the text are labeled. b A head-to-tail USUV-E dimer generated by symmetry operations. The original USUV-E molecule is colored as in panel a, and the symmetry related molecule is in grey. The buried fusion loop is highlighted in green. c Superimposition of the DI of E-structures of JEV serocomplex (E-USUV marked in red ribbon, E-WNV in cyans, and E-JEV in wheat tint); highlighting their E₀F₀ loops (shaded for clarity) and the loop-located α1 helices. d Superimposition of the DI of E-structures of other flaviviruses (the JEV serocomplex members excluded). Clearly shown is that the α1 helix is not present in these structures, and the E₀F₀ loop is of variable conformation. e Structure-based multiple sequence alignment of representative flaviviral E proteins. Horizontal arrows indicate β-strands and spinal lines highlight α-helices. The Asn residue that could be glycosylated in the E₀F₀ loop is marked with a red triangle, and those residues recognized by CR4354 are highlighted with black boxes