FIG. 5.

(A) Induction of basS and ompT gene expression in response to LL-37, PG-1, and PB. Total RNA was extracted from E. coli MG1655 exposed for 15 min to each peptide at the indicated concentrations. Blots were hybridized with basS-, ompT-, and rrlH-specific cDNA probes. The expression levels of basS (open bars) and ompT (filled bars) were determined as described in Materials and Methods and reported as levels of induction (n-fold) in peptide-treated cultures relative to those in cultures of untreated bacteria. Data representative of two independent experiments with similar results are shown. (B) Activity of LL-37, PG-1, and PB against E. coli MG1655. Bacterial cultures were incubated for 15 min at 37°C in the presence of increasing amounts of each peptide, and the numbers of CFU per milliliter were determined. Data are means ± standard deviations of at least three experiments.