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1.
Biochemistry (Mosc) ; 88(2): 202-210, 2023 Feb.
Article in English | MEDLINE | ID: mdl-37072328

ABSTRACT

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.


Subject(s)
Acinetobacter baumannii , Polysaccharides, Bacterial , Polysaccharides, Bacterial/chemistry , Acinetobacter baumannii/genetics , Acinetobacter baumannii/metabolism , Bacterial Capsules/chemistry , Multigene Family
2.
Biochemistry (Mosc) ; 86(4): 506-516, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33941071

ABSTRACT

Rathayibacter sp. VKM Ac-2759 (family Microbacteriaceae, class Actinobacteria) contains two glycopolymers in the cell wall. The main chain of rhamnan, glycopolymer 1, is built from the repeating tetrasaccharide units carrying terminal arabinofuranose residues at the non-reducing end, →3)-α-[α-D-Araf-(1→2)]-D-Rhap-(1→2)-α-D-Rhap-(1→3)-α-D-Rhap-(1→2)-α-D-Rhap-(1→. Similar to other described Rathayibacter species, rhamnose in the neutral glycopolymer of the VKM Ac-2759 strain is present in the D-configuration. Acetalated with pyruvic acid teichuronic acid, glycopolymer 2, is composed of the repeating tetrasaccharide units, →4)-ß-D-GlcpA-(1→4)-ß-D-Galp-(1→4)-ß-D-Glcp-(1→3)-ß-[4,6-S-Pyr]-D-Manp-(1→. Glycopolymers 1 and 2 were identified in prokaryotic microorganisms for the first time and their structures were established by chemical analysis and NMR spectroscopy. The obtained data can be used in taxonomic research, as well as for elucidating the mechanisms of plant colonization and infection by bacteria of the Rathayibacter genus.


Subject(s)
Actinomycetales/metabolism , Cell Wall/metabolism , Uronic Acids/chemistry , Carbohydrate Sequence , Deoxy Sugars , Magnetic Resonance Spectroscopy , Mannans , Pyruvic Acid , Uronic Acids/metabolism
3.
Carbohydr Res ; 474: 67-71, 2019 Feb 15.
Article in English | MEDLINE | ID: mdl-30763794

ABSTRACT

The O-polysaccharide (O-antigen) of Vibrio cholerae O14 was studied using chemical analyses and 1D and 2D NMR spectroscopy. The following structure of the repeating unit of the O-antigen was established: where GlcpN(SHb) indicates 2-deoxy-2-[(S)-3-hydroxybutanoylamino]-d-glucose. We found that Vibrio cholerae O14 is similar to that of O-polysaccharide of Azospirillum brasilense S17, which has been reported earlier. Moreover, we predicted functions of all the genes in the O-antigen gene cluster according to the structure established. Our study enriches the existing O-antigen database of Vibrio cholerae, and further facilitates the bacterial serotype identification.


Subject(s)
Amino Sugars/analysis , Gene Expression Regulation, Bacterial , Multigene Family , O Antigens/genetics , Vibrio cholerae/genetics , Amino Sugars/chemistry , Amino Sugars/metabolism , Azospirillum brasilense/chemistry , Azospirillum brasilense/genetics , Azospirillum brasilense/metabolism , Carbohydrate Sequence , Nuclear Magnetic Resonance, Biomolecular , O Antigens/analysis , O Antigens/chemistry , O Antigens/metabolism , Serotyping , Vibrio cholerae/chemistry , Vibrio cholerae/metabolism , Vibrio cholerae/pathogenicity
4.
Carbohydr Res ; 472: 98-102, 2019 Jan 15.
Article in English | MEDLINE | ID: mdl-30530139

ABSTRACT

O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of Vibrio cholerae O100 and studied by component analyses and 1D and 2D NMR spectroscopy. The following structure of the O-polysaccharide was established: →3)-ß-d-QuipNAc4N(dHh)-(1 → 3)-α-d-Fucp4N(RHb)-(1 → 3)-α-l-FucpNAc-(1→ where Hb and dHh indicate 3-hydroxybutanoyl and 3,5-dihydroxyhexanoyl, respectively. The O-antigen gene cluster of V. cholerae O100 has been sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the OPS structure.


Subject(s)
O Antigens/chemistry , O Antigens/genetics , Sequence Analysis, DNA/methods , Vibrio cholerae/metabolism , Amino Sugars/chemistry , Carbohydrate Sequence , Models, Molecular , Molecular Sequence Annotation , Multigene Family , Nuclear Magnetic Resonance, Biomolecular , Vibrio cholerae/chemistry , Vibrio cholerae/genetics
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