FIG 11.

Assay of relative gene transfer frequencies using the chromosomal marker of rifampin resistance. Abbreviations: WT, the rifampin-resistant strain SB1003; Δ, a deletion of the cckA gene (21); + WT, plasmid pRCckA, expressing the WT cckA gene; + HA, plasmid pCW104, expressing the H399A allele of cckA; + YD, plasmid pRCckA-YD, expressing the Y589D allele. The assays were performed as described elsewhere (21), and the data are normalized to the WT value (average of 516 rifampin-resistant colonies). Error bars indicate standard deviations (n = 3).