Fig. 2.

Bactericidal assays demonstrate that pesticin and the hybrid lysin kill E. coli cells expressing FyuA. Pesticin or hybrid lysin at a concentration of 100 μg/mL was added to E. coli T7 express cells in PBS at 37 °C while shaking. Control cultures had no proteins added. Samples were removed at several time points, plated, and surviving bacterial colonies were counted. These experiments were repeated at least three times. The standard error of the mean is shown. (A) Cells expressing fyuA are killed by pesticin and the hybrid lysin. (B) Cells expressing fyuA and pim are killed by the hybrid lysin but not by pesticin due to protection conferred by the pesticin immunity protein. Note that the immunity protein cannot protect against killing by the hybrid lysin. (C) E. coli T7 express cells transformed with pET20b (Null) are resistant to killing by pesticin or the hybrid lysin because they do not express fyuA on the cell surface.