---
pmid: '12603743'
title: Regulation of Salmonella typhimurium lipopolysaccharide O antigen chain length
  is required for virulence; identification of FepE as a second Wzz.
authors:
- Murray GL
- Attridge SR
- Morona R
journal: Mol Microbiol
year: '2003'
full_text_available: false
doi: 10.1046/j.1365-2958.2003.03383.x
---

# Regulation of Salmonella typhimurium lipopolysaccharide O antigen chain length is required for virulence; identification of FepE as a second Wzz.
**Authors:** Murray GL, Attridge SR, Morona R
**Journal:** Mol Microbiol (2003)
**DOI:** [10.1046/j.1365-2958.2003.03383.x](https://doi.org/10.1046/j.1365-2958.2003.03383.x)

## Abstract

1. Mol Microbiol. 2003 Mar;47(5):1395-406. doi: 10.1046/j.1365-2958.2003.03383.x.

Regulation of Salmonella typhimurium lipopolysaccharide O antigen chain length 
is required for virulence; identification of FepE as a second Wzz.

Murray GL(1), Attridge SR, Morona R.

Author information:
(1)Department of Molecular Biosciences, The University of Adelaide, Adelaide, 
South Australia, Australia, 5005.

Wzz proteins regulate the degree of polymerization of the O antigen (Oag) 
subunits in lipopolysaccharide (LPS) biosynthesis. Although the pathogenic 
relevance of Oag is well recognized, the significance of Oag chain length 
regulation is not well defined. In this report, Salmonella typhimurium was shown 
to possess two functional wzz genes resulting in a bimodal Oag length 
distribution. In addition to the previously described wzzST that results in long 
(L) modal length LPS with 16-35 Oag repeat units (RUs), we now report that 
wzzfepE, a homologue of Escherichia coli fepE, is responsible for the production 
of very long (VL) modal length LPS Oag, estimated to contain> 100 Oag RUs. 
Analysis of a series of isogenic S. typhimurium C5 mutants found that the 
presence of either wzz gene (and hence either modal length) was sufficient for 
complement resistance and virulence in the mouse model of infection, suggesting 
a degree of redundancy in the role of these two wzz genes and their respective 
Oag modal lengths. In contrast, the wzzST/wzzfepE double mutant, with relatively 
short, random-length Oag, displayed enhanced susceptibility to complement and 
was highly attenuated in the mouse. This clearly demonstrates the molecular 
genetic basis for the longer LPS Oag chains previously identified as the basis 
of complement resistance in Salmonella. The presence of wzzfepE homologues in 
the genomic sequences of strains of Escherichia coli, Shigella flexneri and 
multiple serovars of Salmonella suggests that bimodality of LPS Oag is a common 
phenomenon in the Enterobacteriaceae.

DOI: 10.1046/j.1365-2958.2003.03383.x
PMID: 12603743 [Indexed for MEDLINE]