title: The biosynthesis of UDP-d-FucNAc-4N-(2)-oxoglutarate (UDP-Yelosamine) in Bacillus cereus ATCC 14579: Pat and Pyl, an aminotransferase and an ATP-dependent Grasp protein that ligates 2-oxoglutarate to UDP-4-amino-sugars.
abstract: Surface glycan switching is often observed when micro-organisms transition between different biotic and abiotic niches, including biofilms, although the advantages of this switching to the organism are not well understood. Bacillus cereus grown in a biofilm-inducing medium has been shown to synthesize an unusual cell wall polysaccharide composed of the repeating subunit →6)Gal(α1-2)(2-R-hydroxyglutar-5-ylamido)Fuc2NAc4N(α1-6)GlcNAc(β1→, where galactose is linked to the hydroxyglutarate moiety of FucNAc-4-amido-(2)-hydroxyglutarate. The molecular mechanism involved in attaching 2-hydroxyglutarate to 4-amino-FucNAc has not been determined. Here, we show two genes in B. cereus ATCC 14579 encoding enzymes involved in the synthesis of UDP-FucNAc-4-amido-(2)-oxoglutarate (UDP-Yelosamine), a modified UDP-sugar not previously reported to exist. Using mass spectrometry and real time NMR spectroscopy, we show that Bc5273 encodes a C4″-aminotransferase (herein referred to as Pat) that, in the presence of pyridoxal phosphate, transfers the primary amino group of l-Glu to C-4″ of UDP-4-keto-6-deoxy-d-GlcNAc to form UDP-4-amino-FucNAc and 2-oxoglutarate. Pat also converts 4-keto-xylose, 4-keto-glucose, and 4-keto-2-acetamido-altrose to their corresponding UDP-4-amino-sugars. Bc5272 encodes a carboxylate-amine ligase (herein referred as Pyl) that, in the presence of ATP and Mg(II), adds 2-oxoglutarate to the 4-amino moiety of UDP-4-amino-FucNAc to form UDP-Yelosamine and ADP. Pyl is also able to ligate 2-oxoglutarate to other 4-amino-sugar derivatives to form UDP-Yelose, UDP-Solosamine, and UDP-Aravonose. Characterizing the metabolic pathways involved in the formation of modified nucleotide sugars provides a basis for understanding some of the mechanisms used by bacteria to modify or alter their cell surface polysaccharides in response to changing growth and environmental challenges.
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Soyoun
authors.initials: S
authors.lastname: Hwang
authors.affiliation: From the Complex Carbohydrate Research Center and Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
authors.forename: Zi
authors.initials: Z
authors.lastname: Li
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Yael
authors.initials: Y
authors.lastname: Bar-Peled
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Avi
authors.initials: A
authors.lastname: Aronov
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Jaime
authors.initials: J
authors.lastname: Ericson
authors.affiliation: From the Complex Carbohydrate Research Center and Department of Plant Biology, University of Georgia, Athens, Georgia 30602 peled@ccrc.uga.edu.
authors.forename: Maor
authors.initials: M
authors.lastname: Bar-Peled
mesh_terms: D001409:Bacillus cereus / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000235:genetics / Q000378:metabolism*; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D066244:Proton Magnetic Resonance Spectroscopy; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*; D014539:Uridine Diphosphate Sugars / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D014539:Uridine Diphosphate Sugars; D000637:Transaminases; D002222:Carbamoyl-Phosphate Synthase (Ammonia)
keywords: Bacterial Metabolism; Biofilm; Carbohydrate Biosynthesis; Enzyme Catalysis; Glycobiology