tailieunhanh - Báo cáo Y học: Guanosine diphosphate-4-keto-6-deoxy-D-mannose reductase in the pathway for the synthesis of GDP-6-deoxy-D-talose in Actinobacillus actinomycetemcomitans

The serotype a-specific polysaccharide antigen ofActinoba-cillus actinomycetemcomitansis an unusual sugar, (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-a-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 anti-gen from A. actinomycetemcomitansSUNYaB 75 | Eur. J. Biochem. 269 5963-5971 2002 FEBS 2002 doi Guanosine diphosphate-4-keto-6-deoxy-D-mannose reductase in the pathway for the synthesis of GDP-6-deoxy-D-talose in Actinobacillus actinomycetemcomitans Nao Suzuki1 Yoshio Nakano1 Yasuo Yoshida1 Takashi Nezu2 Yoshihiro Terada2 Yoshihisa Yamashita3 w 4 F F B F w w Bl B F F B B B F F B w BB B B B B BB B F F B F F B B B BB BB B B B W B B B B B w w B F F B B B B B B B F F B B BB BB BB B F F B B B B B B B B BB B BB B B B BB B B B B BB and Toshihiko Koga1 1 Department of Preventive Dentistry and 2Department of Prosthetic Dentistry I Kyushu University Faculty of Dental Science Fukuoka Japan 3Department of Oral Health Nihon University School of Dentistry Tokyo Japan 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-a-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-a-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-a-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. Keywords .