FIGURE 9.

Defects in the lipid A biogenesis of Δwaa mutants exhibiting increased rpoEP3 transcriptional activity. Charge deconvoluted ESI FT-ICR mass spectra of isogenic ΔwaaC (A), ΔwaaF (B), ΔwaaG (C), and ΔwaaP (D) in the negative ion mode depicting the lipid A composition and its modifications from the LPS obtained from cultures grown in phosphate-limiting medium at 30 °C. Part of the negative ion mass spectra of the native LPS after unspecific fragmentation, leading to the cleavage of the labile lipid A-Kdo linkage, is presented. The mass peaks corresponding to the hexaacylated lipid A part and substitutions with P-EtN and/or l-Ara4N are indicated.