FIG 1 .

mlaA* mutants lyse because of hyperproduction of LPS. (A) Cells were cultured with or without arabinose (LptFG WT and LptFG low, respectively) to modulate lptFG expression and thus LPS transport. Cells were then transitioned to spent medium, and cell density was monitored (A₆₀₀). The data show that limitation of lptFG expression suppressed cell death caused by the mlaA* mutation. (B) Schematic showing the bla-araC-P_BAD cassette that was introduced into the strains so that lptFG expression could be regulated by an arabinose-inducible promoter (22). (C) Analysis of whole-cell LPS levels indicated that when expression of lptFG in mlaA* mutant cells was limited (LptFG low), LPS levels were lower than those in mlaA* mutant strains with efficient lptFG expression (LptFG WT).