FIG. 3.

Secretion of LLO bearing different N-terminal residues by L. monocytogenes strains growing outside host cells. (A and B) Growth (A) and LLO secretion (B) in LB medium by L. monocytogenes strains that produced either wild-type (WT) Lys-LLO or its derivatives containing other (indicated) N-terminal residues. The relative amounts of secreted X-LLO proteins (in mid-logarithmic [mid log], late-logarithmic [late log], and stationary [stat] phases of growth) were compared by immunoblotting. Shown are the results of one of five independent experiments. The numbers below the first row in panel B (which include standard deviations) refer to the quantitation of immunoblots from three samples taken during mid-exponential growth and analyzed with an Odyssey infrared imager. (C) Hemolytic activity of LLO present in stationary-phase culture supernatants from the L. monocytogenes strains with the indicated mutations. Error bars indicate standard deviations for three replicates in one experiment that is representative of four independent experiments. sRBCs, sheep red blood cells.