Fig. 4.

Residue E47 is required for both integrative and excisive recombination. Recombination reactions between supercoiled attR with radiolabeled, linear attL (A) and supercoiled attP with radiolabeled, linear attB (B) were carried out with IHF, Xis, and the indicated amounts of Int. (C) Kinetics of integrative recombination between supercoiled attP and radiolabeled, linear attB was determined with Int or E47A at 50 nM. The percent recombinant product is plotted as a function of protein concentration (A and B) or time (C).