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A glycopolymer classified as an O-specific polysaccharide had earlier been isolated from the multi-drug resistant nosocomial pathogen Acinetobacter baumannii LUH5533 (serogroup O1) and its chemical structure had been established. In the present work, we found that the glycopolymer was a capsular polysaccharide (CPS), its structure was revised, and 5,7-diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid (di-N-acetyllegionaminic acid) was identified as its component, which had been overlooked earlier. The revised structure is consistent with predicted functions of genes in the CPS biosynthesis cluster classified into the KL7 or PSgc1 group, which is present in the LUH 5533 genome.

Acinetobacter baumannii, capsular polysaccharide structure, legionaminic acid, polysaccharide biosynthesis gene claster

Publication DOI: 10.1007/s11172-015-1000-9
Journal NLM ID: 100912060
Publisher: New York: Consultants Bureau
Correspondence: yknirel@gmail.com; nikvol@obolensk.org; popova_nastya86@mail.ru; striker198126@aliyun.com; mm_shn@mail.ru
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, State Research Center for Applied Microbiology and Biotechnology, Obolensk, 142279, Moscow Region, Russian Federation, Moscow Institute of Physics and Technology, 9 Institutskii per., Dolgoprudny, 141700, Moscow Region, Russian Federation, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Economic-Technological Development Area, Tianjin, 300457, People´s Republic of China, M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 ul. Miklikho-Maklaya, 117997, Moscow, Russian
Methods: 13C NMR, 1H NMR, NMR-2D, de-O-acylation, sugar analysis, GLC, mild acid hydrolysis, Smith degradation, NMR-1D, GPC, bioinformatic analysis

The K5 capsular polysaccharide (CPS) was isolated from the bacterium Acinetobacter baumannii (A. baumannii) SDF and studied by 1D and 2D 1H and 13C NMR spectroscopy before and after O-deacetylation and partial acid hydrolysis. The CPS was found to be composed of branched tetrasaccharide repeats (K units) containing 5,7-diacetamido-3,5,7,9-tetradeoxy-d-glycero-d-galacto-non-2-ulosonic acid (Leg5Ac7Ac). The KL5 capsule biosynthesis gene cluster at the K locus is consistent with the composition and structure of the CPS. KL5 is almost identical to the KL7 gene ulosonic acid (Leg5Ac7Ac A. baumannii LUH5533 that has been characterized earlier, and differs only in the gene for Wzy polymerase that is responsible for the formation of the linkage between the K units. The K5 CPS from strain SDF and the K7 CPS from strain LUH5533 have the same K-unit structure but a different linkage between the K units, which is formed by distinct Wzy polymerases. As opposite to Leg5Ac7Ac in the K7 CPS, this monosaccharide is O-acetylated at position 4 in the K5 CPS. No acetyltransferase for this modification of the K5 CPS is present in the KL5 gene cluster, and hence it is encoded by a gene located elsewhere in the genome.

capsular polysaccharide, Acinetobacter baumannii, legionaminic acid, Wzy polymerase, gene polymorphism, KL gene locus

Publication DOI: 10.1007/s11172-019-2432-4
Journal NLM ID: 100912060
Publisher: New York: Consultants Bureau
Correspondence: YA Knirel
Institutions: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health Queensland University of Technology, Brisbane, Australia, M. M. Shemyakin-Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia, Moscow Institute of Physics and Technology, 9 Institutskii per., Russian Federation, State Research Center for Applied Microbiology and Biotechnology, Obolensk, Russian Federation
Methods: 13C NMR, 1H NMR, NMR-2D, partial acid hydrolysis, sugar analysis, GLC, de-O-acetylation, bioinformatic analysis

Acinetobacter baumannii isolate LUH5553 carries the KL90 capsule gene cluster, which includes genes for three glycosyltransferases (Gtrs) and the ItrA3 initiating transferase, as well as a set of genes for synthesis of a higher sugar, 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic (di-N-acetylpseudaminic) acid (Pse5Ac7Ac). The K90 capsular polysaccharide (CPS) has a tetrasaccharide repeat (K90 unit), which begins with d-GlcpNAc and contains Pse5Ac7Ac. The higher sugar was cleaved by mild acid hydrolysis of the CPS, and structures of the initial and modified polysaccharides were established by 1D and 2D 1H and 13C NMR spectroscopy. K90 contains α-d-Galp-(1-6)-d-GlcpNAc and α-d-GlcpNAc-(1-3)-d-GlcpNAc fragments, and formation of these glycosidic linkages is catalysed respectively by Gtr14 and Gtr15. The gtr14 and gtr15 genes occur in several A. baumannii KL gene clusters, including KL5 and KL7 that carry itrA2 rather than itrA3. As ItrA2 introduces d-GalpNAc rather than d-GlcpNAc as the first monosaccharide, Gtr15 can transfer d-GlcpNAc to either of these amino sugars, suggesting that this enzyme has relaxed specificity. Consequently, the third, novel glycosyltransferase, Gtr163, forms the β-(2-3) linkage between Pse5Ac7Ac and d-Galp. Wzy polymerases encoded by KL90 and KL7 are 54% identical and form the same linkage between the K units to give branched polysaccharides with the same main chain but different disaccharide side chains, β-Pse5Ac7Ac-(2-3)-d-Galp in K90 and α-Leg5Ac7Ac-(2-6)-d-Galp in K7.

capsular polysaccharide, Acinetobacter baumannii, Di-N-Acetylpseudaminic acid, KL90 gene cluster

Publication DOI: 10.1016/j.carres.2019.04.008
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: J.J. Kenyon
Institutions: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russia, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Australia, School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia, M. M. Shemyakin & Y. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russiag Higher Chemical College of the Russian Academy of Sciences, D. I. Mendeleev University of Chemical Technology of Russia, Moscow, Russia
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, GLC, GPC, bioinformatic analysis, mild acid hydroysis

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

The polysaccharide capsule surrounding bacterial cell plays an important role in pathogenesis of infections caused by the opportunistic pathogen Acinetobacter baumannii by providing protection from external factors. The structures of the capsular polysaccharide (CPS) produced by A. baumannii isolates and the corresponding CPS biosynthesis gene clusters are highly diverse, although many of them are related. Many types of A. baumannii CPSs contain isomers of 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acid (DTNA). Three of these isomers, namely acinetaminic acid (l-glycero-l-altro isomer), 8-epiacinetaminic acid (d-glycero-l-altro isomer), and 8-epipseudaminic acid (d-glycero-l-manno isomer), have not been found so far in naturally occurring carbohydrates from other species. In A. baumannii CPSs, DTNAs carry N-acyl substituents at positions 5 and 7; in some CPSs, both N-acetyl and N-(3-hydroxybutanoyl) groups are present. Remarkably, pseudaminic acid carries the (R)-isomer and legionaminic acid carries the (S)-isomer of the 3-hydroxybutanoyl group. The review addresses the structure and genetics of biosynthesis of A. baumannii CPSs containing di-N-acyl derivatives of DTNA.

capsular polysaccharide, Acinetobacter baumannii, nonulosonic acid, Bacterial polysaccharide, capsule, higher monosaccharide, acyl group

NCBI PubMed ID: 37072328
Publication DOI: 10.1134/S0006297923020049
Journal NLM ID: 0376536
Publisher: Nauka/Interperiodica
Correspondence: Y.A. Knirel
Institutions: State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 117913, Russia, Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia, Branch of the Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry in Pushchino, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia