FIG 7.

Crystal structure of the 6-HB formed by MT-WQ-IDL and gp41 NHR. (A) Crystal structures of gp41 NHR+CHR (PDB 2X7R), NHR+MT-C34 (PDB 3VTP), and N46-MT-WQ-IDL (PDB 5H0N) are shown as cartoon representation or electrostatic surface. NHR is colored in gray, CHR in light green, MT-WQ-IDL in forest green, and both the MT and IDL tails in magenta. Important residues are enlarged as sticks and identified. (B) Enlargement of interactions between IDL tail and NHR. NHR is colored in gray, MT-WQ-IDL in forest green, and IDL tail in magenta. IDL tail is shown in stick or cartoon representation. (C, D) Electron density of IDL tail in the N46-MT-WQ-IDL crystal structure. The 2Fo–Fc electron density is drawn as blue meshes at a contour level of 0.8 σ, and Fo–Fc electron density is drawn as red and green meshes at a contour level of 2.6 σ. The omit map (C) was generated with the phases of a molecular replacement solution with preliminary refinement but without the IDL tail modeled from the beginning. (E) Schematic diagram showing the effect of MT-WQ-IDL on the process of HIV entry into host cell. MT-WQ-IDL can bind to the NHR more stably and block the formation of a homologous 6-helix bundle, thus inhibiting viral infection.