Streptococcus suis serotype 3 is counted among the S. suis serotypes causing clinical disease in pigs. Yet, limited information is available on this serotype. Here we determined for the first time the chemical composition and structure of serotype 3 capsular polysaccharide (CPS), a major bacterial virulence factor and the antigen at the origin of S. suis classification into serotypes. Chemical and spectroscopic data gave the repeating unit sequence for serotype 3: [4)D-GlcA (β1-3)d-QuiNAc4NAc(β1-]n. To the best of our knowledge, this is the first report of di-N-acetyl-d-bacillosamine (QuiNAc4NAc) containing polysaccharides in Streptococci and the second time this rare diamino sugar has been observed in a Gram-positive bacterial species since its initial report. This led to the identification of homologues of UDP-QuiNAc4NAc synthesis genes in S. suis serotype 18. Thus, the repeating unit sequence for serotype 18 is: [3)d-GalNAc(α1-3)[d-Glc (β1-2)]d-GalA4OAc(β1-3)d-GalNAc(α1-3)d-QuiNAc4NAc(α1-]n. A correlation between S. suis serotypes 3 and 18 CPS sequences and genes of these serotypes' cps loci encoding putative glycosyltransferases and polymerase responsible for the biosynthesis of the repeating unit was tentatively established. Knowledge of CPS structure and composition will contribute to better dissect the role of this bacterial component in the pathogenesis of S. suis serotypes 3 and 18.
polysaccharide, capsular polysaccharide, polysaccharides, carbohydrate structure, Streptococcus suis, Di-N-Acetyl-bacillosamine, Serotype 18, Serotype 3
NCBI PubMed ID: 30014879Publication DOI: 10.1016/j.carres.2018.07.003Journal NLM ID: 0043535Publisher: Elsevier
Correspondence: mariela.segura@umontreal.ca
Institutions: Swine and Poultry Infectious Diseases Research Center, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte St., St-Hyacinthe, Quebec, J2S 2M2, Canada, Canadian Glycomics Network (GlycoNet), University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada, National Research Council, 100 Sussex Dr., Ottawa, Ontario, K1A 0R6, Canada, Division of Bacterial and Parasitic Disease, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu, 501-1193, Japan
Methods: 13C NMR, 1H NMR, periodate oxidation, gel filtration, NMR-2D, GC-MS, de-O-acylation, sugar analysis, methanolysis, SEC-MALS, bioinformatic analysis
Found