Acinetobacter baumannii K116 capsular polysaccharide structure is a hybrid of the K14 and revised K37 structures

• Published in: Carbohydrate research 2019-10, Vol.484, p.107774-107774, Article 107774
• Main Authors: Shashkov, Alexander S., Cahill, Sarah M., Arbatsky, Nikolay P., Westacott, Amy C., Kasimova, Anastasiya A., Shneider, Mikhail M., Popova, Anastasiya V., Shagin, Dmitry A., Shelenkov, Andrey A., Mikhailova, Yuliya V., Yanushevich, Yurii G., Edelstein, Mikhail V., Kenyon, Johanna J., Knirel, Yuriy A.
• Format: Article
• Language: English
• Subjects: Acinetobacter baumannii; Acinetobacter baumannii - enzymology; Acinetobacter baumannii - genetics; Acinetobacter baumannii - metabolism; Bacterial Capsules - chemistry; Bacterial Capsules - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Capsular polysaccharide; Carbohydrate Sequence; Evolution, Molecular; Genome, Bacterial; Glycosyltransferases - genetics; Glycosyltransferases - metabolism; K locus; K116; K14; Multigene Family; Polysaccharides, Bacterial - biosynthesis; Polysaccharides, Bacterial - chemistry; Revised K37; Whole Genome Sequencing
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2019.107774

The genome of Acinetobacter baumannii clinical isolate, MAR-303, recovered in Russia was sequenced and found to contain a novel gene cluster at the A. baumannii K locus for capsule biosynthesis. The gene cluster, designated KL116, included four genes for glycosyltransferases (Gtrs) and a gene for a Wzy polymerase responsible for joining oligosaccharide K units into the capsular polysaccharide (CPS). The arrangement of KL116 was a hybrid of previously described A. baumannii gene clusters, with two gtr genes and the wzy gene shared by KL37 and the two other gtr genes found in KL14. The structure of the K116 CPS was established by sugar analysis and Smith degradation, along with one- and two-dimensional 1H and 13C NMR spectroscopy. The CPS is composed of branched pentasaccharide K units containing only neutral sugars, with three monosaccharides in the main chain and a disaccharide side chain. The K116 unit shares internal sugar linkages with the K14 and K37 units, corresponding to the presence of shared gtr genes in the gene clusters. However, the specific linkage formed by Wzy was discrepant between K116 and the previously reported K37 CPS produced by A. baumannii isolate NIPH146. The K37 structure was therefore revised in this study, and the corrected Wzy linkage found to be identical to the Wzy linkage in K116. The KL116, KL14 and KL37 gene clusters were found in genomes of a variety of A. baumannii strain backgrounds, indicating their global distribution. [Display omitted] •The Acinetobacter baumannii K116 capsule structure is established and is closely related to K14 and K37 capsules.•Correlation to capsule biosynthesis genes revealed an error in the K37 structure, which was revised in this study.•The function of the glycosyltransferases, Wzy polymerases and initiating transferase were unambiguously assigned.