FIG. 3.

Inhibition of MLV and FIV integrases by l-chicoric acid. (A) MLV integrase. The reaction was carried out at 37°C for 60 min under conditions as described previously (15). The reaction contained 50 nM MLV integrase, 5 nM U5 DNA substrate, and l-chicoric acid. Lane 1 shows a reaction without integrase. Lane 2 shows a reaction done in the absence of inhibitors; an equal volume of water was added instead. The numbers above the figure indicate the concentration of l-chicoric in the reaction. (B) FIV integrase. The reaction was carried out at 37°C for 60 min with 5 nM FIV U5 substrate (52) and the indicated concentrations of l-chicoric acid in the absence (lane 1) or presence of 75 nM wild-type (WT; lanes 2 to 4), C-terminal truncated (ΔC; lanes 5 to 7), or N-terminal truncated variants (ΔN; lanes 8 to 10) of FIV integrase. Numbers in parentheses represent the amino acid residues of the protein. The full-length and the truncated derivatives of FIV integrase contained a poly-His tag at the N terminus. The presence of the tag restores the 3′-end processing and joining activities of the truncated variants (52). In both panels A and B, the open and filled arrowheads indicate the positions of the labeled substrate and the processed product, respectively. The 3′-end joining products are indicated by IP.