title: Guanosine diphosphate-4-keto-6-deoxy-d-mannose reductase in the pathway for the synthesis of GDP-6-deoxy-d-talose in Actinobacillus actinomycetemcomitans.
abstract: The serotype a-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans is an unusual sugar, 6-deoxy-d-talose. Guanosine diphosphate (GDP)-6-deoxy-d-talose is the activated sugar nucleotide form of 6-deoxy-d-talose, which has been identified as a constituent of only a few microbial polysaccharides. In this paper, we identify two genes encoding GDP-6-deoxy-d-talose synthetic enzymes, GDP-alpha-d-mannose 4,6-dehydratase and GDP-4-keto-6-deoxy-d-mannose reductase, in the gene cluster required for the biosynthesis of serotype a-specific polysaccharide antigen from A. actinomycetemcomitans SUNYaB 75. Both gene products were produced and purified from Escherichia coli transformed with plasmids containing these genes. Their enzymatic reactants were analysed by reversed-phase HPLC (RP-HPLC). The sugar nucleotide produced from GDP-alpha-d-mannose by these enzymes was purified by RP-HPLC and identified by electrospray ionization-MS, 1H nuclear magnetic resonance, and GC/MS. The results indicated that GDP-6-deoxy-d-talose is produced from GDP-alpha-d-mannose. This paper is the first report on the GDP-6-deoxy-d-talose biosynthetic pathway and the role of GDP-4-keto-6-deoxy-d-mannose reductase in the synthesis of GDP-6-deoxy-d-talose.
authors.affiliation: Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, Fukuoka, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Suzuki
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Nakano
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Takashi
authors.initials: T
authors.lastname: Nezu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Terada
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Koga
mesh_terms: D000188:Actinobacillus / Q000201:enzymology* / Q000378:metabolism; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D003837:Deoxy Sugars / Q000096:biosynthesis* / Q000302:isolation & purification; D008401:Gas Chromatography-Mass Spectrometry; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006601:Hexoses / Q000096:biosynthesis* / Q000302:isolation & purification; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D017931:DNA Primers; D003837:Deoxy Sugars; D006601:Hexoses; D006153:Guanosine Diphosphate; C011754:6-deoxytalose; D007658:Ketone Oxidoreductases