In Yersinia pseudotuberculosis complex, the O-antigen of LPS is used for the serological characterization of strains, and 21 serotypes have been identified to date. The O-antigen biosynthesis gene cluster and corresponding O-antigen structure have been described for 18, leaving O:8, O:13 and O:14 unresolved. In this study, two O:8 isolates were examined. The O-antigen gene cluster sequence of strain 151 was near identical to serotype O:4a, though a frame-shift mutation was found in ddhD, while No. 6 was different to 151 and carried the O:1b gene cluster. Structural analysis revealed that No. 6 produced a deeply truncated LPS, suggesting a mutation within the waaF gene. Both ddhD and waaF were cloned and expressed in 151 and No. 6 strains, respectively, and it appeared that expression of ddhD gene in strain 151 restored the O-antigen on LPS, while waaF in No. 6 resulted in an LPS truncated less severely but still without the O-antigen, suggesting that other mutations occurred in this strain. Thus, both O:8 isolates were found to be spontaneous O-antigen-negative mutants derived from other validated serotypes, and we propose to remove this serotype from the O-serotyping scheme, as the O:8 serological specificity is not based on the O-antigen.
O-antigen, O-specific polysaccharide, Yersinia pseudotuberculosis, serotyping, O-antigen gene cluster, O-antigen biosynthesis, O:8 serotype
NCBI PubMed ID: 26873504Publication DOI: 10.1177/1753425916631403Journal NLM ID: 101469670Publisher: Sage Publications
Correspondence: decastro@unina.it
Institutions: Division of Structural Biochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Borstel, Germany, Helsinki University Central Hospital Laboratory Diagnostics, Helsinki, Finland, Department of Chemical Sciences, University of Napoli, Napoli, Italy, Department of Bacteriology and Immunology, Medicum, and Research Programs Unit, Immunobiology, University of Helsinki, Helsinki, Finland, School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia, Department of Agriculture Sciences, University of Napoli, Portici, Italy
Methods: 13C NMR, 1H NMR, NMR-2D, PCR, SDS-PAGE, DNA techniques, ESI-MS, DOC-PAGE, Western blotting, composition analysis, NMR-1D, genetic methods, GPC, de-N-acylation, hydrazinolysis, function analysis of gene clusters, ESI-IT-TOF-MS/MS