REVIEW: 5,7-Diamino-3,5,7,9-tetradeoxynon-2-ulosonic Acids in the Capsular Polysaccharides of Acinetobacter baumannii

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Yuriy A. Knirel^1,a*, Anastasia A. Kasimova^1,b, Nikolay P. Arbatsky^1,c, Mikhail M. Shneider^2,d, Anastasia V. Popova^3,e, Fedor A. Brovko^4,f, Aleksander S. Shashkov^1,g, Sofia N. Senchenkova^1,h, Andrei V. Perepelov^1,i, and Anna M. Shpirt^1,j

¹Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Russia

²Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia

³State Research Center for Applied Microbiology and Biotechnology, 142279 Obolensk, Moscow Region, Russia

⁴Branch of the Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry in Pushchino, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia

^* To whom correspondence should be addressed.

Received December 18, 2022; Revised January 16, 2023; Accepted January 19, 2023

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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.

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KEY WORDS: Acinetobacter baumannii, capsular polysaccharide, bacterial polysaccharide, capsule, acyl group, higher monosaccharide, nonulosonic acid

DOI: 10.1134/S0006297923020049

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