FIG 2.

Phenotypes of spontaneously arising pilQ mutants. (A) The MIC of penicillin G (MIC_penG) was determined for strains harboring one of the 13 different class 1 mutations in pilQ, as well as the parental strain (SZ3) and SZ3 pilQ2. The error bars indicate standard errors of the mean. (B) Transformation efficiencies of the 13 class 1 pilQ-backcrossed mutants, SZ3, and SZ3 pilQ2. Each strain was transformed with a plasmid (pSY6) carrying a gyrB allele that confers resistance to nalidixic acid (Nal^r). SZ3 is a variant of strain RM11.2 that contains an inducible recA allele that allows IPTG control of pilin antigenic variation. Each of the strains used in this experiment contained the same pilE sequence to minimize the influence of different PilE sequences on transformation efficiency. (C) Scanning electron microscopy was used to examine SZ3 and three pilQ mutants with normal, ablated, and reduced transformation efficiencies (left to right).