Fig. 3: Isolated sAD retains a similar structure to the apical domain of TfR1.
From: Rational design of universal immunotherapy for TfR1-tropic arenaviruses
a The asymmetric unit contains four copies of the sAD/GP1MACV complex. Each of the eight chains is shown using a unique color. The chains are rendered as tubes with radii proportional to the B-factor. The protein pairs in the asymmetric unit differ in quality of the electron density; some have a low B-factors (e.g., green/cyan), while others are less defined and hence have higher B-factor (e.g., purple/orange). Regardless, the sAD/GP1 interface is identical in all pairs. b Crystal structure of sAD in complex with GP1MACV. The GP1 domain is shown using surface representation (white), and sAD is presented as a ribbon diagram in rainbow colors from the N′ terminus (blue) to the C′ terminus (red). N-linked glycans and Tyr211 of sAD are shown using sticks. c The sAD adopts the same overall structure as the apical domain of hTfR1. A ribbon diagram showing the apical domain of hTfR1 (PDB ID: 3KAS) in orange superimposed on sAD, shown in blue. The right view is rotated 90° with respect to the view on the left. Tyr211, a central residue at the interface with GP1, is shown. Residues 301–326 of hTfR1, which were omitted in sAD, are colored pink. d A ribbon diagram showing the structure of the complex between sAD and GP1MACV, in blue and white, respectively, superimposed on the hTfR1/GP1MACV complex (PDB ID: 3KAS), colored orange and gray, respectively. The long loop that connects strands βII-6 and βII-7 changes position in sAD compared to hTfR1 and is highlighted in green (sAD). This loop in hTfR1 originally included residues 301–326 (pink), which were eliminated from sAD. e Similar superimposition as in d, showing the charge–charge interaction between GP1MACV and sAD or hTfR1. The negatively charged Glu294 of hTfR1 forms a salt bridge with Lys169 from GP1. In the case of sAD, Glu340 from αII-2, which replaces an alanine residue of hTfR1, projects in the same direction as Glu294 of hTfR1. This Glu340 of sAD forms a similar salt bridge with Lys169 of GP1MACV.
