Figure 2. Interactions between Ad11 knob and CD46-4D, and comparison with the structure of the knob in complex with CD46-2D.
(A) Overall contact region for one CD46 molecule (red) bound to two Ad11 knob protomers (blue and green). CD46 domains SCR1 and SCR2 contact the extensive loops of the knob protomers. The HI and DG loops are from the blue protomer, whereas the GH and IJ loops are from the green protomer. Superimposed onto the CD46-4D structure (red) is a ribbon drawing of the CD46-2D structure (grey), which was also determined in complex with Ad11 knob [32]. The superposition was performed using Ad11 knob residues only. The three main contact regions (areas 1, 2 and 3) are boxed, and are shown in atomic detail in panels (B), (C) and (D), respectively. Hydrogen bonds and salt bridges (distance<3.5 Å) present in complexes with CD46-2D and CD46-4D are represented with black dashed lines, whereas similar interactions only present in the complex with CD46-2D are shown in orange dashed lines.