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- Title
A plasmid--encoded rfb<sub>O:5A</sub> gene cluster is required for biosynthesis of the 0:54 antigen in <em>Salmonella enterica</em> serovar Borreze.
- Authors
Keenleyside, Wendy J.; Perry, Malcolm; Maclean, Leann; Poppe, Cornelius; Whitfield, Chris
- Abstract
Previous studies demonstrated that the presence of a 7-8 kb plasmid is correlated with expression of the lipopolysaccharide (LPS) 0:54 antigen in several <em>Salmonella enterica</em> serovars. In this study, a 6.7 kb plasmid from a field isolate of <em>S. enterica</em> serovar Borreze was shown to encode enzymes responsible for the synthesis of the 0:54 polysaccharide. Curing the plasmid results In simultaneous loss of smooth 0-polysaccharide-substituted LPS molecules and 0:54 serotype. SDS-PAGE analysis of other 0:54 isolates indicated that the O:54 O-polysaccharide can be co-expressed with an additional O-polysaccharide, likely encoded by chromosomal genes. The structure of the O:54 polysaccharide was determined by a combination of chemical and nuclear magnetic resonance (NMR) methods and was found to be an unusual homopolymer of N-acetylmannosamine (o-ManNAc) residues. The polysaccharide contained a disaccharide repeating unit with the structure: →4)-β-D-ManPNAc-(1 → 3)-β-D-ManpNAc-(1→ This structure does not resemble other 0-polysaccharides in S. enterica. To examine the role played by plasmid functions in synthesis of the 0:54 polysaccharide, the 6.7 kb plasmid was cloned to produce a hybrid plasmid (pWQ800) in pGEM-7Zf(+). In <em>Escherichia coli</em> K-12 Δrfb, pWQ800 directed the synthesis of authentic 0:54 polysaccharide. Polymerized 0:54 polysaccharide was also produced in <em>S. enterica</em> serovar Typhimurium <em>rfb</em> and <em>rfc</em> mutants. From these data, we conclude that pWQ800 carries the <em>rfb</em>0:54 gene cluster and synthesis of the 0:54 polysaccharides does not require host chromosomal <em>rfb</em> functions. However, synthesis of the 0:54 polysaccharide requires the function of the <em>rfe</em> and <em>rffE</em> genes which are part of the gene cluster encoding enzymes involved in biosynthesis of enterobacterial common antigen. The <em>rffE</em> gene product synthesizes the 0:54 precursor...
- Subjects
STATISTICAL correlation; PLASMIDS; ENDOTOXINS; ANTIGENS; SALMONELLA; POLYSACCHARIDE synthesis; NUCLEAR magnetic resonance
- Publication
Molecular Microbiology, 1994, Vol 11, Issue 3, p437
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.1994.tb00325.x