title: Molecular divergence of the sia locus in different serogroups of Neisseria meningitidis expressing polysialic acid capsules.
abstract: The serogroups B, C, W135 and Y of Neisseria meningitidis express chemically and immunologically distinct capsular polysaccharides containing sialic acid. In the case of serogroup B meningococci sialic acid is synthesized by the gene products of a locus termed sia and forms the homopolymers of the capsule. The organization of the genes required for sialic acid synthesis in serogroups B, C, W135 and Y was elucidated by PCR technology. Cloning, sequencing and the functional expression of the polysialyltransferase (PST) genes of serogroups B and C demonstrated that the difference in capsule composition derives from the presence of related, but distinct siaD genes coding for PSTs. Analysis of meningococci of serogroups W135 and Y expressing sialic acid heteropolymers revealed that the DNA sequences of the corresponding genetic loci in these serogroups were highly homologous, but differed completely from the siaD genes of serogroups B and C. This finding suggests that enzymes unrelated to those of serogroups B and C are required for the formation of sialic acid heteropolymers characteristic of the capsules of serogroups W135 and Y.
authors.affiliation: Institut für Hygiene und Mikrobiologie, Universität Würzburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Claus
authors.forename: U
authors.initials: U
authors.lastname: Vogel
authors.forename: M
authors.initials: M
authors.lastname: Mühlenhoff
authors.forename: R
authors.initials: R
authors.lastname: Gerardy-Schahn
authors.forename: M
authors.initials: M
authors.lastname: Frosch
mesh_terms: D005075:Biological Evolution; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D014644:Genetic Variation; D009345:Neisseria meningitidis / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017421:Sequence Analysis; D012703:Serotyping; D012794:Sialic Acids / Q000378:metabolism*; D012799:Sialyltransferases / Q000235:genetics* / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D012794:Sialic Acids; C071290:alpha(2-8)polysialic acid; D012799:Sialyltransferases