FIG. 4.
Vesicles produced by strains with mutations in σE response pathway genes are released intact. (A) Electron micrographs of vesicles from the wild type and mutant strains MK6D31, MK5B7, and MK11F26. Size bar, 100 nm. (B) Equilibrium density gradients of vesicles from the wild type and mutant strains (listed in the panel A legend). Periplasm from DH5α was applied to the same gradient (bottom panel). Fraction 1 is the least dense; fraction 10 is the most dense. Prominent vesicle protein bands are visible in light fractions by Coomassie blue (CB)-stained SDS-PAGE; MBP was visualized by immunoblotting (α-MBP). rseA::Tn5 samples were concentrated by precipitation with 20% trichloroacetic acid.