Figure 2. Details of DNA conformations, recognition, and active site mechanics during strand transfer.

a, Cartoon representation of the viral and target DNAs in the TCC_Apo (left panel) and STC (right panel) structures. b, Mechanics of DNA strand transfer. Superposition of common elements within TCC_ddA, STC, and Mn²⁺-loaded intasome⁴ (PDB ID 3L2S). Carbon atoms of viral DNA and IN active site residues are painted orange (3L2S) and yellow (STC), respectively. c, Close in view of the integration site in the STC structure. d, IN interactions with the tDNA backbone. Dashed lines indicate hydrogen bonds.