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Type K82 capsular polysaccharide (CPS) was isolated from Acinetobacter baumannii LUH5534. The structure of a linear tetrasaccharide repeating unit of the CPS was established by sugar analysis along with one- and two-dimensional 1H and 13C NMR spectroscopy. Proteins encoded by the KL82 capsule gene cluster in the genome of LUH5534 were assigned to roles in the synthesis of the K82 CPS. In particular, functions were assigned to two new glycosyltransferases (Gtr152 and Gtr153) and a novel pyruvyltransferase, Ptr5, responsible for the synthesis of d-galactose 4,6-(R)-pyruvic acid acetal.

Acinetobacter baumannii, capsular polysaccharide structure, biotechnology, Pyruvic acid acetal, K locus, genetics of capsule biosynthesis

NCBI PubMed ID: 30200867
Publication DOI: 10.1134/S0006297918070064
Journal NLM ID: 0376536
Publisher: Nauka/Interperiodica
Correspondence: yknirel@gmail.com; nastia-kasimova979797@mail.ru
Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia, School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia, Higher Chemical College of the Russian Academy of Sciences, D. I. Mendeleev University of Chemical Technology of Russia, Moscow, Russia, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russia, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, GLC, mild acid hydrolysis, GPC, dialysis, bioinformatic analysis (BLASTp)

Bacterial extracellular polysaccharides are known as a cell-bound capsule, a sheath, or a slime, which is excreted into the environment. They play an important role in virulence of medical bacteria and plant-to-symbiont interaction and are used for serotyping of bacteria and production of vaccines. Some exopolysaccharides have commercial applications in industry, and claims of health benefits have been documented for an increasing number of them. Exopolysaccharides have diverse composition and structure, and some contain sugar and non-sugar components that are found in bacterial carbohydrates only. The present article provides an updated collection of the data on exopolysaccharides of various classes of gram-negative and gram-positive bacteria reported until the end of 2019. When known, biosynthesis pathways of exopolysaccharides are treated in a summary manner. References are made to structure and biosynthesis relatedness between exopolysaccharides of different bacterial taxa as well as between bacterial polysaccharides and mammalian glycosaminoglycans.

polysaccharide structure, Gram-negative bacteria, capsule, Biofilm, polysaccharide biosynthesis, gram-positive bacteria, Monosaccharide composition, Bacterial exopolysaccharide, non-sugar component

Publication DOI: 10.1016/B978-0-12-819475-1.00005-5
Publisher: Elsevier
Correspondence: marie-rose.vancalsteren@canada.ca; yknirel@gmail.com
Editors: Barchi J, Kamerling H
Institutions: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada

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

Acinetobacter baumannii, capsular polysaccharide structure, biotechnology, Pyruvic acid acetal, K locus, genetics of capsule biosynthesis