title: Identification and Biochemical Characterization of the Novel α2,3-Sialyltransferase WbwA from Pathogenic Escherichia coli Serotype O104.
abstract: The sialyl-T antigen sialylα2-3Galβ1-3GalNAc is a common O-glycan structure in human glycoproteins and is synthesized by sialyltransferase ST3Gal1. The enterohemorrhagic Escherichia coli serotype O104 has the rare ability to synthesize a sialyl-T antigen mimic. We showed here that the wbwA gene of the E. coli O104 antigen synthesis gene cluster encodes an α2,3-sialyltransferase WbwA that transfers sialic acid from CMP-sialic acid to Galβ1-3GalNAcα-diphosphate-lipid acceptor. Nuclear magnetic resonance (NMR) analysis of purified WbwA enzyme reaction product indicated that the sialyl-T antigen sialylα2-3Galβ1-3GalNAcα-diphosphate-lipid was synthesized. We showed that the conserved His-Pro (HP) motif and Glu/Asp residues of two EDG motifs in WbwA are important for the activity. The characterization studies showed that WbwA from E. coli O104 is a monofunctional α2,3-sialyltransferase and is distinct from human ST3Gal1 as well as all other known sialyltransferases due to its unique acceptor specificity. This work contributes to knowledge of the biosynthesis of bacterial virulence factors.
  
  
  OBJECTIVE
  This is the first characterization of a sialyltransferase involved in the synthesis of an O antigen in E. coli. The enzyme contributes to the mimicry of human sialyl-T antigen and has unique substrate specificity but very little sequence identity to other sialyltransferases. Thus, the bacterial sialyltransferase is related to the human counterpart only by the similarity of biochemical activity.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
authors.forename: Diana
authors.initials: D
authors.lastname: Czuchry
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Desormeaux
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Stuart
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Jarvis
authors.affiliation: TumorEnd, Baton Rouge, Louisiana, USA.
authors.forename: Khushi L
authors.initials: KL
authors.lastname: Matta
authors.affiliation: Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
authors.forename: Walter A
authors.initials: WA
authors.lastname: Szarek
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada brockhau@queensu.ca.
authors.forename: Inka
authors.initials: I
authors.lastname: Brockhausen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D019158:N-Acetylneuraminic Acid / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D019081:O Antigens / Q000096:biosynthesis*; D017422:Sequence Analysis, DNA; D012799:Sialyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
chemical_list: D029968:Escherichia coli Proteins; D019081:O Antigens; D012799:Sialyltransferases; C000606155:WbwA protein, E coli; C029156:N-acetyllactosaminide alpha-2,3-sialyltransferase; D019158:N-Acetylneuraminic Acid; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase