FIGURE 6.

DegP degrades LptD when the LPS biosynthesis is inhibited. Escherichia coli wild-type (wt), ΔdegP, and ΔbepA cells were grown in the LB-Lennox medium at 30°C. When cells reached OD₆₀₀ = 0.1, they were treated with 1xMIC of LPC-058 (LpxC inhibitor). Untreated cells were used as the control. (A) For the analysis of the steady-state level Lpt proteins, cell growth was monitored by OD₆₀₀ measurements. When the growth curves of treated and untreated cells separate (arrow), samples for western blot analysis were taken. Time points indicate the minutes after the growth curves separated. * indicates the degradation product of LptA. (B) OM fractions were purified from cells treated for 2 h with LPC-058. Equal amounts of proteins were loaded (upper panel). Crude extracts of the same cultures were analyzed by western blot, using anti-OmpA antibodies, and equal amounts of cells were loaded (lower panel, 0.67 OD₆₀₀). Growth curves and western blot analyses shown are representative of at least three independent experiments.