CSDB: Search results

References to other databases: GTC:G44879CL, GlycomeDB:27292
Structural formula & atomic coordinates
Sweet-II 3D model
Show glycosyltransferases

Lipooligosaccharide (LOS) is a major virulence factor of the pathogenic NEISSERIA: Nine lgt genes at three chromosomal loci (lgt-1, 2, 3) encoding the glycosyltransferases responsible for the biosynthesis of LOS oligosaccharide chains were examined in 26 Neisseria meningitidis, 51 Neisseria gonorrhoeae and 18 commensal Neisseria strains. DNA hybridization, PCR and nucleotide sequence data were compared to previously reported lgt genes. Analysis of the genetic organization of the lgt loci revealed that in N. meningitidis, the lgt-1 and lgt-3 loci were hypervariable genomic regions, whereas the lgt-2 locus was conserved. In N. gonorrhoeae, no variability in the composition or organization of the three lgt loci was observed. lgt genes were detected only in some commensal Neisseria species. The genetic organization of the lgt-1 locus was classified into eight types and the lgt-3 locus was classified into four types. Two types of arrangement at lgt-1 (II and IV) and one type of arrangement at lgt-3 (IV) were novel genetic organizations reported in this study. Based on the three lgt loci, 10 LOS genotypes of N. meningitidis were distinguished. Phylogenetic analysis revealed a gene cluster, lgtH, which separated from the homologous genes lgtB and lgtE. The lgtH and lgtE genes were mutually exclusive and were located at the same position in lgt-1. The data demonstrated that pathogenic and commensal Neisseria share a common lgt gene pool and horizontal gene transfer appears to contribute to the genetic diversity of the lgt loci in Neisseria

biosynthesis, oligosaccharide structure, Neisseria meningitidis, Neisseria, gene cluster, glycosyltransferases, Gonorrhoeae, Neisseria gonorrhoeae, genetic diversity, lipooligosaccharide (LOS), phylogenetic analysis, virulence factor

NCBI PubMed ID: 12055303
Journal NLM ID: 0376646
Publisher: Washington, DC: Kluwer Academic/Plenum Publishers
Correspondence: zhu@cber.fda.gov
Institutions: Division of Bacterial, Parasitic and Allergenic Products and Division of Viral Products, Center for Biologics Evaluation and Research, FDA, 8800 Rockville Pike, Bethesda, MD, USA
Methods: PCR, DNA sequencing, DNA techniques, genetic methods, RT-PCR

Lipopolysaccharides (LPS) are the endotoxins of Gram-negative bacteria and very well known for their immunological, pharmacological and pathophysiological effects displayed in eucaryotic cells and organisms. To date, much emphasis has been put on the elucidation of the chemical structures of LPS and on their relation, or that of substructures, to the various biological effects. The lipid part of LPS, the lipid A, was proven to represent the toxic principle of endotoxin. However, lipid A toxicity depends strongly on its structure, and is influenced by a second region of LPS, the core region, that is covalently linked to lipid A. Also, the core region possesses immunogenic properties. Therefore, complete structural analyses of the core region and the comparison of its structures with biological features of LPS are of high importance for a better understanding of LPS action, and one prerequesite for strategies aimed at the treatment of endotoxicosis. In the past, quite a number of structures of the core regions from various Gram-negative bacteria were published and summarized in several overviews. The present review adds to this knowledge those structures that were published between October 1998 and December 2001.

lipopolysaccharides, heptose, Kdo, chemical structure, core region, tructure

Publication DOI: 10.4052/tigg.14.87
Journal NLM ID: 9425898
Correspondence: oholst@fz-borstel.de
Institutions: Structural Biochemistry, Research Center Borstel, Center for Medicine and Biosciences, Borstel, Germany

References to other databases: GTC:G96123DT, GlycomeDB:1818
Structural formula & atomic coordinates
Sweet-II 3D model
Show glycosyltransferases

Helicobacter pylori is a prevalent bacterial, gastroduodenal pathogen of humans that can express Lewis (Le) and related antigens in the O-chains of its surface lipopolysaccharide. The O-chains of H. pylori are commonly composed of internal Le(x) units with terminal Le(x) or Le(y) units or, in some strains, with additional units of Le(a), Le(b), Le(c), sialyl-Le(x) and H-1 antigens, as well as blood groups A and B, thereby producing a mosaicism of antigenic units expressed. The genetic determination of the Le antigen biosynthetic pathways in H. pylori has been studied, and despite striking functional similarity, low sequence homology occurs between the bacterial and mammalian α(1,3/4)- and α(1,2)-fucosyltransferases. Factors affecting Le antigen expression in H. pylori, that can influence the biological impact of this molecular mimicry, include regulation of fucosyltransferase genes through slipped-strand mispairing, the activity and expression levels of the functional enzymes, the preferences of the expressed enzyme for distinctive acceptor molecules and the availability of activated sugar intermediates. Le mimicry was initially implicated in immune evasion and gastric adaptation by the bacterium, but more recent studies show a role in gastric colonization and bacterial adhesion with galectin-3 identified as the gastric receptor for polymeric Le(x) on the bacterium. From the host defence aspect, innate immune recognition of H. pylori by surfactant protein D is influenced by the extent of LPS fucosylation. Furthermore, Le antigen expression affects both the inflammatory response and T-cell polarization that develops after infection. Although controversial, evidence suggests that long-term H. pylori infection can induce autoreactive anti-Le antibodies cross-reacting with the gastric mucosa, in part leading to the development of gastric atrophy. Thus, Le antigen expression and fucosylation in H. pylori have multiple biological effects on pathogenesis and disease outcome.

molecular mimicry, Helicobacter pylori, Fucosyltransferases, bacterial pathogenesis, Lewis antigens, fucosylation

NCBI PubMed ID: 18279843
Publication DOI: 10.1016/j.carres.2007.12.012
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: anthony.moran@nuigalway.ie
Institutions: Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland, Institute for Glycomics, Gold Coast Campus, Griffith University, Queensland 4222, Australia
Methods: NMR, sugar analysis, MS, genetic methods