FIG. 1.

Characteristics of LPS of S. enterica serovar Typhimurium strains used in this study. (A) Schematic representation of OAg in S. enterica serovar Typhimurium. WT S. enterica serovar Typhimurium processes LPS species with trimodal OAg lengths, i.e., VL-, L-, and S-OAg. A new set of isogenic mutant strains was generated, as well as low-copy-number plasmids for complementation of the mutations. The mutant strains deficient in the synthesis of the entire OAg (waaL) possesses only the core oligosaccharide (core OS) of LPS. Mutant strains defective in the regulators of L-OAg (wzz_ST) or VL-OAg (wzz_fepE) and a wzz_ST wzz_fepE double mutant strain contain LPS species with bimodal or monomodal OAg lengths, as indicated. (B) WT Salmonella and various mutant strains were grown in LB broth, and bacterial cells were processed for LPS analyses by SDS-polyacrylamide gel electrophoresis and silver staining. The mutant strains were complemented by plasmids harboring the deleted gene and the native promoters. The presence and absence of plasmids for complementation (compl.) are indicated by + and −, respectively.