FIG 8.

Conservation and orientation of the PD in EBOV GP₁. (A) EBOV GP₁ base and head subdomains (PDB accession number 3CSY) comprising the PD, shown in an orientation similar to that of the PD of orthoretroviruses in Fig. 6. The β-strand and selected loop regions are labeled and colored as described in the legends of Fig. 5 and 6. Disulfides in the apical region are shown as sticks. (B and C) EBOV (PDB accession number 5HJ3) (B) and HIV-1 (PDB accession number 4TVP) (C) trimeric envelope protein crystal structures shown from the top, distal side. The apical domain in the GP₁ protomers in panel B and the distal region of the inner domains and the outer domains of gp120 in panel C are omitted for clarity. The β-sandwich, terminal β-strand, and layer 1 homologues are shown in green, wheat, and blue. Region H and β-strand 3 homologues are shown in red and light blue and highlighted with red and light blue asterisks. The arrows in panel B indicate the clockwise direction of the major 120° rotation of GP₁ relative to gp120 protomers in the trimeric structures. (D and E) The same structures as the ones in panels B and C, rotated 90°, with the virion-proximal side facing up.