The repeat unit of the K12 capsular polysaccharide isolated from the Acinetobacter baumannii global clone 1 clinical isolate, D36, was elucidated by means of chemical and spectroscopical methods. The structure was shown to contain N-acetyl-D-galactosamine (D-GalpNAc), N-acetyl-D-fucosamine and N-acetyl-L-fucosamine linked together in the main chain, with the novel sugar, 5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-altro-non-2-ulosonic acid (5,7-di-N-acetylacinetaminic acid or Aci5Ac7Ac), attached to D-GalpNAc as a side branch. This matched the sugar composition of the K12 capsule and the genetic content of the KL12 capsule gene cluster reported previously. D-FucpNAc was predicted to be the substrate for the initiating transferase, ItrB3, with the Wzy polymerase making a α-D-FucpNAc-(1 → 3)-D-GalpNAc linkage between the repeat units. The three glycosyltransferases encoded by KL12 are all retaining glycosyltransferases and were predicted to form specific linkages between the sugars in the K12 repeat unit.
Acinetobacter baumannii, capsular polysaccharide, K locus, KL12 gene cluster, acinetaminic acid
NCBI PubMed ID: 25926563Publication DOI: 10.1093/glycob/cwv028Journal NLM ID: 9104124Publisher: IRL Press at Oxford University Press
Correspondence: ruth.hall@sydney.edu.au
Institutions: School of Molecular Bioscience, The University of Sydney, Sydney, NSW, 2006, Australia, Department of Chemical Sciences, University of Napoli, Napoli, Italy
Methods: 13C NMR, 1H NMR, methylation, NMR-2D, GC-MS, sugar analysis, mild acid hydrolysis, NMR-1D, acetylation, bioinformatic analysis, SEC
Found