Novel factors required for OM integrity.

(A) Genetic interaction sub-network in rich medium. (B) Aggravating interactions between lptD and yfgH, yceK, and ytfN. (C) Proposed mechanism of drug hypersensitivity (I) modeled on [68]: envelope deficiency results in a porous OM (dashes), thereby allowing vancomycin (VAN) into the periplasm where it blocks PG cross-linking, weakening the cell wall and resulting in cytoplasmic membrane bulges in single mutant strains (II) or catastrophic cell wall failure and lysis in double mutants (III); scale bar equals 2 µm. Quantification (percentage) of bulged or lysed cells following vancomycin treatment according to strain genotype; error bars indicate standard deviation (IV). (D) Growth inhibition of strains treated with vancomycin. Graph shows mean drug disk halo diameter and standard deviation (error bars) in three independent experiments; p-value calculated using Student's t-test. (E) SDS-PAGE immunoblot analyses of marker protein levels in indicated strains during logarithmic growth in rich medium; periplasmic maltose-binding protein (MBP) used as loading control.