Acinetobacter baumannii K106 and K112: Two Structurally and Genetically Related 6-Deoxy-l-talose-Containing Capsular Polysaccharides

Int J Mol Sci. 2021 May 26;22(11):5641. doi: 10.3390/ijms22115641.


Whole genome sequences of two Acinetobacter baumannii clinical isolates, 48-1789 and MAR24, revealed that they carry the KL106 and KL112 capsular polysaccharide (CPS) biosynthesis gene clusters, respectively, at the chromosomal K locus. The KL106 and KL112 gene clusters are related to the previously described KL11 and KL83 gene clusters, sharing genes for the synthesis of l-rhamnose (l-Rhap) and 6-deoxy-l-talose (l-6dTalp). CPS material isolated from 48-1789 and MAR24 was studied by sugar analysis and Smith degradation along with one- and two-dimensional 1H and 13C NMR spectroscopy. The structures of K106 and K112 oligosaccharide repeats (K units) l-6dTalp-(1→3)-D-GlcpNAc tetrasaccharide fragment share the responsible genes in the respective gene clusters. The K106 and K83 CPSs also have the same linkage between K units. The KL112 cluster includes an additional glycosyltransferase gene, Gtr183, and the K112 unit includes α l-Rhap side chain that is not found in the K106 structure. K112 further differs in the linkage between K units formed by the Wzy polymerase, and a different wzy gene is found in KL112. However, though both KL106 and KL112 share the atr8 acetyltransferase gene with KL83, only K83 is acetylated.

Keywords: 6-deoxy-l-talose; Acinetobacter baumannii; K locus; K106; K112; capsular polysaccharide.

MeSH terms

  • Acinetobacter baumannii* / chemistry
  • Acinetobacter baumannii* / genetics
  • Acinetobacter baumannii* / metabolism
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Deoxy Sugars* / chemistry
  • Deoxy Sugars* / genetics
  • Deoxy Sugars* / metabolism
  • Glycosyltransferases / genetics
  • Glycosyltransferases / metabolism
  • Hexoses* / chemistry
  • Hexoses* / genetics
  • Hexoses* / metabolism
  • Polysaccharides, Bacterial* / chemistry
  • Polysaccharides, Bacterial* / genetics
  • Polysaccharides, Bacterial* / metabolism
  • Species Specificity


  • Bacterial Proteins
  • Deoxy Sugars
  • Hexoses
  • Polysaccharides, Bacterial
  • 6-deoxytalose
  • Glycosyltransferases