Acinetobacter baumannii produces a variety of capsular polysaccharides (CPS) via genes located at the chromosomal K locus and some KL gene clusters include genes for the synthesis of specific sugars. The structures of K11 and K83 CPS produced by isolates LUH5545 and LUH5538, which carry related KL11a and KL83 gene clusters, respectively, were established by sugar analysis and one- and two-dimensional 1H and 13C NMR spectroscopy. Both CPS contain l-rhamnose (l-Rha) and 6-deoxy-l-talose (l-6dTal), and both KL gene clusters include genes for dTDP-l-Rhap synthesis and a tle (talose epimerase) gene encoding an epimerase that converts dTDP-l-Rhap to dTDP-l-6dTalp. The K11 and K83 repeat units are the same pentasaccharide, consisting of d-glucose, l-Rha, l-6dTal, and N-acetyl-d-glucosamine, except that l-6dTal is 2-O-acetylated in K83. However, the K units are linked differently, with l-Rha in the main chain in K11, but as a side-branch in K83. KL11 and KL83 encode unrelated Wzy polymerases that link the K units together and different acetyltransferases, though only Atr8 from KL83 is active. The substrate specificity of each Wzy polymerase was assigned, and the functions of all glycosyltransferases were predicted. The CPS structures produced by three closely related K loci, KL29, KL105 and KL106, were also predicted.
capsular polysaccharide, Acinetobacter baumannii, 6-deoxy-L-talose
NCBI PubMed ID: 28528003Publication DOI: 10.1016/j.ijbiomac.2017.05.082Journal NLM ID: 7909578Publisher: Butterworth-Heinemann
Correspondence: johanna.kenyon@qut.edu.au
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, M. M. Shemyakin & Y. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia, State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russia, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia, School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, PR China
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, acid hydrolysis, GLC, Smith degradation, de-O-acetylation, GPC, bioinformatic analysis