Fig. 3: Absence of CpxA induces Lipid-A modifications.

Representative mass spectra of Lipid-A from intact parent (WT) bacteria grown at 37 °C (A) and 26 °C (B), ΔcpxA bacteria grown at 37 °C (C) and 26 °C (D), ΔcpxA complementation strain ΔcpxA/pWKS_cpxA grown at 37 °C (E) and 26 °C (F) as well as an empty plasmid control ΔcpxA/pWKS grown at 37 °C (G) and 26 °C (H). Spectra was acquired using matrix-assisted laser desorption ionization (MALDI). A set of 5 peaks was identified as unique Lipid-A species and their respective chemical classifications are provided in Table 1. The peak at m/z 1642.3 is identified as a 4-amino-L-arabinose (L-Ara4N) modification of a penta-acylated Lipid-A (red), and the peak at m/z 1822.7 as hexa-acylated Lipid-A (green). Dashed line represents the expected location of a peak that is not present.