FIG 5.

pilA2 expression is regulated through temperature and multiple transcriptional factors. (A) Schematic of the type IV pilus biosynthesis operon containing the pilA2 gene. The predicted intrinsic transcriptional terminators and ΔG values are indicated. The arrows represent transcriptional units. (B to D) Northern blot analyses of the pilA2 gene. 23S and 16S rRNAs stained with methylene blue are represented as loading controls at the bottom of the gels. In each lane, 2 μg of total RNA was loaded. (B) Expression of pilD-pilA2 polycistronic and pilA2 monocistronic mRNA at 25 or 37°C. (C) pilA2 expression in wild-type C. perfringens grown to the exponential (E; OD₆₀₀ of 1.5 to 2.0), early stationary (ES; OD₆₀₀ of 4.5 to 5.0), mid-stationary (MS; 2 and 8 h after OD₆₀₀ reached 4.5 at 25 and 37°C, respectively), and late-stationary (LS; 4 and 16 h after OD₆₀₀ reached 4.5 at 25 and 37°C, respectively) phases. (D) pilA2 expression in ctrAB, spo0A, and abrB mutants grown to the mid-exponential phase at 25 or 37°C.