FIGURE 5.

Defects in the lipid A biogenesis of ΔlapB derivatives. Shown are charge-deconvoluted ESI FT-ICR mass spectra in the negative ion mode depicting the lipid A composition and its modifications from the LPS obtained under permissive growth conditions. The relevant genotype corresponding to panels A–D is indicated. Part of the negative ion mass spectra of the native LPS after nonspecific fragmentation, leading to the cleavage of the labile lipid A-Kdo linkage, is presented. The mass peaks corresponding to the penta- and hexaacylated lipid A part and substitutions with P-EtN and/or Ara4N are indicated. Insets, predicted chemical composition of the hexa- and pentaacylated lipid A part.