The K46 and K5 capsular polysaccharides produced by Acinetobacter baumannii NIPH 329 and SDF have related structures and the side-chain non-ulosonic acids are 4-O-acetylated by phage-encoded O-acetyltransferases

• DOI: 10.1371/journal.pone.0218461
• Publication Date: 2019-06-20T17:38:41Z
• Authors: Johanna J. Kenyon; Nikolay P. Arbatsky; Mikhail M. Shneider; Anastasiya V. Popova; Andrei S. Dmitrenok; Anastasiya A. Kas...; Alexander S. Shas...; Ruth M. Hall; Yuriy A. Knirel
• Keywords: Acinetobacter baumannii; Acetyltransferases; Acetyltransferases; Gene cluster; Tetrasaccharide

Acinetobacter baumannii isolate NIPH 329 carries a novel capsular polysaccharide (CPS) gene cluster, designated KL46, that is closely related to the KL5 locus in A. SDF but includes genes for synthesis of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic (di-N-acetylpseudaminic) acid (Pse5Ac7Ac) instead corresponding D-glycero-D-galacto isomer (di-N-acetyllegionaminic acid) (Leg5Ac7Ac). In agreement with genetic content chemical studies K46 CPS produced by revealed branched tetrasaccharide repeat (K unit) an overall structure same as K5 from â-Pse5Ac7Ac replacing α-Leg5Ac7Ac. As K5, unit begins d-GalpNAc and α-d-GlcpNAc-(1→3)-d-GalpNAc α-d-Galp-(1→6)-d-GlcpNAc linkages, formed Gtr14 Gtr15 glycosyltransferases, respectively. The Gtr94K46 glycosyltransferase, which Gtr13K5, links Pse5Ac7Ac d-Galp growing K via â-(2→6) linkage. Nearly identical Wzy enzymes connect units α-D-GalpNAc-(1→3)-α-D-Galp linkage form CPSs. Both Leg5Ac7Ac are acetylated at O4 no acetyltransferase present KL46 or KL5. Related acetyltransferases were found encoded genomes, not other strains carrying unacetylated Pse Leg derivative CPS. encoding different putative phage genomes. However, rare among >3000 publically available genome sequences.