Fig. 5.

Different substitutions at residue Q115 can activate recombination. Site I × site I recombination was assayed in vivo with Q115 mutants (R, C, K, Y or E) and WT Sin (+); resH × resH recombination was also assayed with Q115E Sin and WT Sin. Pooled colonies from indicator plates were grown in liquid culture (∼60 generations), and uncut plasmid DNA was analysed by agarose gel electrophoresis. The substrate, product and Sin-expressing plasmids are indicated. All the mutations except Q115E activate recombination.