2Higher Chemical College of the Russian Academy of Sciences, Dmitry Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
3Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 119997 Moscow, Russia; E-mail: email@example.com
4Moscow Institute of Physics and Technology, 141701 Dolgoprudny, Moscow Region, Russia; E-mail: firstname.lastname@example.org
5State Research Center for Applied Microbiology and Biotechnology, 142279 Obolensk, Moscow Region, Russia
6Department of Clinical Microbiology, Christian Medical College, Vellore, 632004 Tamil Nadu, India; E-mail: email@example.com
7Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA; E-mail: firstname.lastname@example.org
* To whom correspondence should be addressed.
Received October 13, 2016; Revision received November 5, 2016
Capsular polysaccharide (CPS) assigned to the K93 type was isolated from the bacterium Acinetobacter baumannii B11911 and studied by sugar analysis along with one- and two-dimensional 1H and 13C NMR spectroscopy. The CPS was found to contain a derivative of pseudaminic acid, and the structure of the branched tetrasaccharide repeating unit was established. Genes in the KL93 capsule biosynthesis locus were annotated and found to be consistent with the CPS structure established. The K93 CPS has the α-d-Galp-(1→6)-β-d-Galp-(1→3)-d-GalpNAc trisaccharide fragment in common with the K14 CPS of Acinetobacter nosocomialis LUH 5541 and A. baumannii D46. It also shares the β-d-Galp-(1→3)-d-GalpNAc disaccharide fragment and the corresponding predicted Gal transferase Gtr5, as well as the initiating GalNAc-1-P transferase ItrA2, with a number of A. baumannii strains.
KEY WORDS: Acinetobacter baumannii, capsular polysaccharide structure, capsule biosynthesis locus, pseudaminic acid, glycosyltransferase