CSDB: Search results

The lipopolysaccharide of Escherichia coli O156 was degraded under mild acidic and alkaline conditions and the resulting polysaccharides were studied by sugar analysis and (1)H and (13)C NMR spectroscopy. The following structure of the pentasaccharide repeating unit of the O-polysaccharide was established: where Rpyr indicates R-configurated pyruvic acid acetal. Minor O-acetyl groups also were present and tentatively localized on the Gal residues. The gene cluster for biosynthesis of the O-antigen of E. coli O156 was analyzed and shown to be consistent with the O-polysaccharide structure.

O-antigen, Escherichia coli, O-polysaccharide, bacterial polysaccharide structure, pyruvic acid, O-antigen gene cluster

NCBI PubMed ID: 27177202
Publication DOI: 10.1016/j.carres.2016.04.025
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: yknirel@gmail.com
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, acid hydrolysis, GLC, mild alkaline degradation, NMR-1D, GPC, mild acid degradation, function analysis of gene clusters

Bacterial surface glycans perform a diverse and important set of biological roles, and have been widely used in the treatment of bacterial infectious diseases. The majority of bacterial surface glycans are decorated with diverse rare functional groups, including amido, acetamidino, carboxamido and pyruvate groups. These functional groups are thought to be important constituents for the biological activities of glycans. Chemical synthesis of glycans bearing these functional groups or their variants is essential for the investigation of structure-activity relationships by a medicinal chemistry approach. To date, a broad choice of synthetic methods is available for targeting the different rare functional groups in bacterial surface glycans. This article reviews the structures of naturally occurring rare functional groups in bacterial surface glycans, and the chemical methods used for installation of these groups.

chemical synthesis, acetamidino group, amido group, bacterial surface glycan, carboxamido group, pyruvyl ketal

NCBI PubMed ID: 35750381
Publication DOI: 10.1016/S1875-5364(22)60177-8
Journal NLM ID: 101504416
Publisher: Beijing: Science Press; Elsevier
Correspondence: J. Yin
Institutions: Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China, Wuxi School of Medicine, Jiangnan University, Wuxi, China

Carbapenemase and extended beta-lactamase-producing Klebsiella pneumoniae isolates represent a major health threat, stimulating increasing interest in immunotherapeutic approaches for combating Klebsiella infections. Lipopolysaccharide O antigen polysaccharides offer viable targets for immunotherapeutic development, and several studies have described protection with O-specific antibodies in animal models of infection. O1 antigen is produced by almost half of clinical Klebsiella isolates. The O1 polysaccharide backbone structure is known, but monoclonal antibodies raised against the O1 antigen showed varying reactivity against different isolates that could not be explained by the known structure. Reinvestigation of the structure by NMR spectroscopy revealed the presence of the reported polysaccharide backbone (glycoform O1a), as well as a previously unknown O1b glycoform composed of the O1a backbone modified with a terminal pyruvate group. The activity of the responsible pyruvyltransferase (WbbZ) was confirmed by western immunoblotting and in vitro chemoenzymatic synthesis of the O1b terminus. Bioinformatic data indicate that almost all O1 isolates possess genes required to produce both glycoforms. We describe the presence of O1ab-biosynthesis genes in other bacterial species and report a functional O1 locus on a bacteriophage genome. Homologs of wbbZ are widespread in genetic loci for the assembly of unrelated glycostructures in bacteria and yeast. In K. pneumoniae, simultaneous production of both O1 glycoforms is enabled by the lack of specificity of the ABC transporter that exports the nascent glycan, and the data reported here provide mechanistic understanding of the capacity for evolution of antigenic diversity within an important class of biomolecules produced by many bacteria.

Lipopolysaccharide, O antigen, Klebsiella pneumoniae, antigenic diversity, vaccine candidate

NCBI PubMed ID: 37428935
Publication DOI: 10.1073/pnas.2301302120
Journal NLM ID: 7505876
Publisher: National Academy of Sciences
Correspondence: F. Serventi ; C. Whitfield
Institutions: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada, LimmaTech Biologics AG, Schlieren 8952, Switzerland, Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada, Institute of Biological Chemistry, Academia Sinica, Taipei, Nangang 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan
Methods: 13C NMR, 1H NMR, NMR-2D, SDS-PAGE, ESI-MS, mild acid hydrolysis, Western blotting, genetic methods, enzyme assay, LC-MS, bioinformatic analysis, SEC, phylogenetic analysis, monoclonal antibodies