FIG. 1.

(a) Schematic representation of the three domains of HIV-2 IN. The N-terminal domain contains a helix-turn-helix motif (HTH) and the zinc-coordinating residues HHCC. The catalytic core (spanning amino acids to 50 to 212) has the three active site residues DD(35)E. The C-terminal nonspecific DNA binding domain has an SH3-like fold. For complementation experiments, the N-terminal domain (IN_1–55, spanning amino acids 1 to 55) of HIV-2 IN is mixed with the N-terminal deletion mutant of HIV-2 IN (ΔN, comprising amino acids 50 to 293). (b) Complementation between an N-terminal deletion mutant of HIV-2 IN (ΔN HIV) and the N-terminal domain of HIV-2 IN (IN₅₅). In the left lane, IN₅₅ is omitted from the reaction; in the middle and right lanes, increasing amounts of IN₅₅ (20 and 200 pmol) are mixed with the N-terminal deletion mutant (7 pmol) prior to the reaction (see Materials and Methods). The substrate (S) represents the precleaved HIV-2 U5 end; strand transfer products are indicated on the left (P).