FIG 1.

The ΔsurA Δskp mutant is lethal and defective in OMP biogenesis at the normal temperature of 37°C but not at the heat shock temperature of 44°C. (A) Growth curves of the indicated strains cultured in liquid medium at 37°C or 44°C. (B) Colony formation on the solid medium (petri dishes) at 37°C or 44°C after serial culture dilutions for the indicated strains. (C) Immunoblotting of folded OMPs in the indicated cell lysates that were separated by seminative SDS-PAGE and detected by using the antibodies against OmpF and OmpC. The boiled cell lysates were included to indicate the positions of the unfolded OMPs, BamB was used as a loading control, and SurA was also analyzed to confirm its complete depletion in the ΔsurA Δskp cells. All the cells used for this experiment were precultured overnight at 37°C before being subjected to growth analysis by subculture at 37°C or 44°C for 6 h (liquid medium) or overnight (solid medium). For the ΔsurA Δskp cells, l-arabinose was added to induce the complementary expression of SurA during the overnight preculturing stage but was removed by centrifugation and washing before subculture. The specificity of the antibodies against OmpC and OmpF used in these analyses was verified using ΔompF and ΔompC cells and is shown in Fig. S1 in the supplemental material. The gene designations indicate the genes that were deleted.