Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Host organism: Homo sapiens
Associated disease: pneumonia [ICD11:
CA40 
];
urinary tract infections (UTI) [ICD11:
GC08 ];
infection due to Acinetobacter baumannii [ICD11:
XN8LS ]
NCBI PubMed ID: 29668902Publication DOI: 10.1093/glycob/cwy037Journal NLM ID: 9104124Publisher: IRL Press at Oxford University Press
Correspondence: mariofeldman
wustl.edu
Institutions: National Research Council Canada, Human Health Therapeutics, Ottawa, Ontario, Canada K1A 0R6, Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA, VaxNewMo LLC, St. Louis, MO 63108, USA
Acinetobacter baumannii is an opportunistic human pathogen with the highest reported rates of multidrug resistance among Gram-negative pathogens. The capsular polysaccharide of A. baumannii is considered one of its most significant virulence factors providing resistance against complemented-mediated killing. Capsule synthesis in A. baumannii is usually initiated by the phosphoglycosyltransferase PglC. PglC transfers a phosphosugar from a nucleotide diphosphate-sugar to a polyprenol phosphate generating a polyprenol diphosphate-linked monosaccharide. Traditionally, PglC was thought to have stringent specificity towards UDP-N-N'-diacetylbacillosamine (UDP-diNAcBac). In this work we demonstrate that A. baumannii PglC has the ability to utilize three different UDP-sugar substrates: UDP-N-acetylglucosamine (UDP-GlcNAc), UDP-N-acetylgalactosamine (UDP-GalNAc) or UDP-diNAcBac. Using phylogenetic analyses, we first demonstrate that A. baumannii PglC orthologs separate into three distinct clades. Moreover, all members within a clade are predicted to have the same preference for one of the three possible sugar substrates. To experimentally determine the substrate specificity of each clade, we utilized in vivo complementation models and NMR analysis. We demonstrate that UDP-diNAcBac is accommodated by all PglC orthologs, but some orthologs evolved to utilize UDP-GlcNAc or UDP-GalNAc in a clade-dependent manner. Furthermore, we show that a single point mutation can modify the sugar specificity of a PglC ortholog specific for UDP-diNAcBac and that introduction of a non-native PglC ortholog into A. baumannii can generate a new capsule serotype. Collectively, these studies begin to explain why A. baumannii strains have such highly diverse glycan repertoires.
serotype, Acinetobacter baumannii, capsular polysaccharide, capsule, PglC, phosphoglycosyltransferase
Structure type: polymer chemical repeating unit
Location inside paper: fig.3
Compound class: CPS, O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_130648,IEDB_135813,IEDB_136906,IEDB_137340,IEDB_137472,IEDB_137473,IEDB_140529,IEDB_141794,IEDB_141807,IEDB_142488,IEDB_146664,IEDB_151528,IEDB_151531,IEDB_167069,IEDB_190606,IEDB_983931,SB_192,SB_21,SB_7
Methods: 13C NMR, SDS-PAGE, Western blotting, genetic methods, cloning, phylogenetic analysis1H NMR
Comments, role: wild-type A. baumannii 17978 strain; published polymerization frame was shifted for consistency with other records.
Related record ID(s): 12606, 12607, 12608
NCBI Taxonomy refs (TaxIDs): 470Reference(s) to other database(s): GTC:G47927SM, GlycomeDB:
37288
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There is only one chemically distinct structure:
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