Fig. 1

Structure of HIV-1 integrase with a native N-terminus (PDB 6VRG). a Structure of IN 1F_NTD–CCD. NTDs are colored in red and CCDs are colored in blue. Zn²⁺ (grey), K⁺ (purple), and phosphate (orange and red) atoms are shown as spheres. b Comparison of the ɑ1 helix between IN 1F and IN GSH (PDB 1K6Y). The IN 1F NTD adopts a helical structure starting from the carbonyl of F1. The IN GSH NTD shows a disruption of the ɑ1 helix. c View highlighting differences between IN 1F and IN GSH at the N-terminus, with a deviation of 4.6 Å in the peptide backbone at L2 and a 10.4 Å deviation in side chain position. This change is accompanied by a flip of ~ 180° in the orientation of the N-terminus. 2Fo-Fc electron density (d) and simulated annealing omit (e) maps contoured at 1.5 σ unambiguously demonstrate the N-terminal structure of IN 1F