PCR analyses of wild type and mutants. (a) Agarose gel electrophoresis of PCR products. Plasmid DNA from strain AC100 was template for lanes 1 to 5 and from AC101 for lanes 6 and 7. Primer sets for each lane were as follows: lanes 1 and 6, primer sets B and E; lane 2, primer sets B and F; lane 3, primer sets C and F; lane 4, primer sets C and E; lanes 5 and 7, primer sets A and D. (b) Scheme of primer annealing sites in sequenced region. Nucleotide sequences of primers are described in Materials and Methods. Arrows show primer annealing sites.