Structure of repeating unit of the capsular polysaccharide from Acinetobacter baumannii D78 and assignment of the K4 gene cluster

Johanna J Kenyon; Immacolata Speciale; Ruth M Hall; Cristina De Castro

doi:10.1016/j.carres.2016.07.016

Structure of repeating unit of the capsular polysaccharide from Acinetobacter baumannii D78 and assignment of the K4 gene cluster

Carbohydr Res. 2016 Nov 3:434:12-17. doi: 10.1016/j.carres.2016.07.016. Epub 2016 Jul 15.

Authors

Johanna J Kenyon¹, Immacolata Speciale², Ruth M Hall³, Cristina De Castro⁴

Affiliations

¹ School of Molecular Bioscience, University of Sydney, Australia; Institute of Health and Biomedical Innovation, Queensland University of Technology, Australia.
² Department of Chemical Sciences, University of Napoli, Italy.
³ School of Molecular Bioscience, University of Sydney, Australia.
⁴ Department of Agricultural Sciences, University of Napoli, Italy. Electronic address: decastro@unina.it.

PMID: 27509201
DOI: 10.1016/j.carres.2016.07.016

Abstract

The structure of the K4 capsular polysaccharide (CPS) from a multiply antibiotic resistant Acinetobacter baumannii isolate D78 was elucidated by chemical and spectroscopical analysis. The K4 repeating unit is composed entirely by aminosugars and the trisaccharide repeating unit of the backbone polysaccharide is branched with a terminal N-acetyl-galactosamine capped with pyruvate as cyclic acetal. Each residue is in the pyranose form, α configured at the anomeric center, and has the D absolute configuration. The genes responsible for the synthesis of the K4 repeat unit and its polymerization and export are found in the capsule locus KL4 present in D78. The pyruvate acetal addition to galactosamine is formed by Ptr1, a novel pyruvate transferase, encoded at this locus.

Keywords: Acinetobacter baumannii; CPS; NMR; Pyruvate acetal; Pyruvate transferase; Structure.

MeSH terms

Acinetobacter baumannii / chemistry*
Amino Sugars / chemistry
Bacterial Capsules / chemistry*
Bacterial Capsules / genetics*
Genes, Bacterial
Molecular Structure
Multigene Family
Trisaccharides / chemistry

Substances

Amino Sugars
Trisaccharides
capsular polysaccharide K4