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Updated: Sep 3, 2025

The Application of Open Searching-based Approaches for the Identification of Acinetobacter baumannii O-linked Glycopeptides
Published on: November 2, 2021
Structure of the K98 capsular polysaccharide from Acinetobacter baumannii REV-1184 containing a cyclic pyruvic acid
Anastasiya A Kasimova1, Mikhail M Shneider2, Mikhail V Edelstein3
1N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia.
Abstract:
The K98 capsular polysaccharide (CPS) from the Acinetobacter baumannii clinical isolate, REV-1184, was studied by sugar analysis and Smith degradation along with one- and two-dimensional 1H and 13C NMR spectroscopy and high-resolution electrospray ionization mass spectrometry. The CPS was found to consist of linear tetrasaccharide repeats (K-units) that include one residue each of d-GlcpNAc, d-GalpNAc, 2-acetamido-2-deoxy-d-galacturonic acid (d-GalpNAcA), and 2-acetamido-2,6-dideoxy-d-glucose (N-acetylquinovosamine, d-QuipNAc), with the GalpNAc residue decorated with a (R)-configurated 4,6-pyruvic acid acetal group. The CPS has a similar composition to that of A. baumannii K4 but the topology of the tetrasaccharide K-unit is different (linear in K98 versus branched in K4). This was due to a difference in sequence for the Wzy polymerases encoded by the CPS biosynthesis gene clusters KL98 and KL4, with the WzyK98 polymerase forming a β-d-QuipNAc-(1→3)-d-GalpNAc linkage between the K98 units.
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