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Taxonomic group: bacteria / Firmicutes (Phylum: Firmicutes)
Host organism: Homo sapiens
Associated disease: pneumonia [ICD11: CA40

]; septicemia [ICD11: MA15.Y

]; meningitis [ICD11: 1D01

]; infection due to Streptococcus agalactiae [ICD11: XN0KC

]

NCBI PubMed ID: 29666608
Publication DOI: 10.3389/fmicb.2018.00545
Journal NLM ID: 101548977
Publisher: Lausanne: Frontiers Research Foundation
Correspondence: mariela.segura

umontreal.ca
Institutions: Faculty of Veterinary Medicine, Swine and Poultry Infectious Disease Research Centre, University of Montreal, Saint-Hyacinthe, QC, Canada, Division of Bacterial and Parasitic Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan, Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada

The capsular polysaccharide (CPS) represents a key virulence factor for most encapsulated streptococci. Streptococcus suis and Group B Streptococcus (GBS) are both well-encapsulated pathogens of clinical importance in veterinary and/or human medicine and responsible for invasive systemic diseases. S. suis and GBS are the only Gram-positive bacteria which express a sialylated CPS at their surface. An important difference between these two sialylated CPSs is the linkage between the side-chain terminal galactose and sialic acid, being α-2,6 for S. suis but α-2,3 for GBS. It is still unclear how sialic acid may affect CPS production and, consequently, the pathogenesis of the disease caused by these two bacterial pathogens. Here, we investigated the role of sialic acid and the putative effect of sialic acid linkage modification in CPS synthesis using inter-species allelic exchange mutagenesis. To this aim, a new molecular biogenetic approach to express CPS with modified sialic acid linkage was developed. We showed that sialic acid (and its α-2,6 linkage) is crucial for S. suis CPS synthesis, whereas for GBS, CPS synthesis may occur in presence of an α-2,6 sialyltransferase or in absence of sialic acid moiety. To evaluate the effect of the CPS composition/structure on sialyltransferase activity, two distinct capsular serotypes within each bacterial species were compared (S. suis serotypes 2 and 14 and GBS serotypes III and V). It was demonstrated that the observed differences in sialyltransferase activity and specificity between S. suis and GBS were serotype unrestricted. This is the first time that a study investigates the interspecies exchange of capsular sialyltransferase genes in Gram-positive bacteria. The obtained mutants represent novel tools that could be used to further investigate the immunomodulatory properties of sialylated CPSs. Finally, in spite of common CPS structural characteristics and similarities in the cps loci, sialic acid exerts differential control of CPS expression by S. suis and GBS.

phenotype, capsular polysaccharide, group B Streptococcus, infectious disease, specificity, sialyltransferase, Streptococcus suis, 3 sialic acid, 6 sialic acid, alpha-2

Structure type: polymer chemical repeating unit
Location inside paper: fig.1, GBS III
Trivial name: PS-III
Compound class: CPS, EPS, polysaccharide
Contained glycoepitopes: IEDB_1083493,IEDB_1083495,IEDB_130646,IEDB_130697,IEDB_135813,IEDB_136044,IEDB_136794,IEDB_137340,IEDB_137472,IEDB_137776,IEDB_1391966,IEDB_1392542,IEDB_140108,IEDB_140110,IEDB_140122,IEDB_141794,IEDB_141807,IEDB_142344,IEDB_142351,IEDB_142487,IEDB_142488,IEDB_143634,IEDB_146100,IEDB_146107,IEDB_146664,IEDB_149138,IEDB_149139,IEDB_149141,IEDB_149142,IEDB_149143,IEDB_149144,IEDB_149145,IEDB_149147,IEDB_149148,IEDB_149149,IEDB_149150,IEDB_149151,IEDB_149174,IEDB_150933,IEDB_151531,IEDB_161524,IEDB_190606,IEDB_423120,IEDB_983931,SB_115,SB_116,SB_131,SB_145,SB_165,SB_166,SB_170,SB_171,SB_172,SB_173,SB_187,SB_192,SB_195,SB_30,SB_39,SB_6,SB_68,SB_7,SB_84,SB_88

Methods: 13C NMR, 1H NMR, gel filtration, NMR-2D, DNA techniques, genetic methods, SEC-MALS, RT-PCR, statistical analysis, transmission electron microscopy, hydrophobicity test
Comments, role: published chemical repeating unit frame was shifted for the uniformity of structures in the database

Related record ID(s): 12772, 12774, 12775, 12776, 12969
NCBI Taxonomy refs (TaxIDs): 216495
Reference(s) to other database(s): GTC:G35073UM, GlycomeDB:11408, CCSD:43274, CBank-STR:17387
Show glycosyltransferases

There is only one chemically distinct structure:

*O[C@@H]1[C@@H](CO)O[C@@H](OC[C@H]2O[C@@H](O[C@@H]3[C@@H](O)[C@H](*)O[C@H](CO)[C@@H]3O)[C@H](NC(C)=O)[C@@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@H](O)[C@H](O[C@]3(C(=O)O)C[C@H](O)[C@@H](NC(C)=O)[C@H]([C@H](O)[C@H](O)CO)O3)[C@H]2O)[C@H](O)[C@H]1O

SVG MW SMILES 3D mol Ionize