FIG. 3.

In vivo cleavage of λ CI repressor by mutant RecA proteins. Derivatives of JAM267 carrying pTrecA220 or mutant derivatives were treated as described in Materials and Methods. The strain marked ΔrecA carried pBR322. Each panel represents the results of a representative experiment. For each mutant strain, a time course is shown. The lanes marked “0” contain samples taken without treatment; those marked “20” and “40” were taken 20 and 40 min after the addition of nalidixic acid (50 μg/ml). The samples were analyzed by Western blotting with antibody against λ CI (see Materials and Methods). The name of the mutation is shown above each set of samples. The location of intact CI is shown; the band just above CI is a cross-reacting protein. wt, wild type.