title: Studies of the biosynthesis of 3,6-dideoxyhexoses: molecular cloning and characterization of the asc (ascarylose) region from Yersinia pseudotuberculosis serogroup VA.
abstract: The 3,6-dideoxyhexoses are found in the lipopolysaccharides of gram-negative bacteria, where they have been shown to be the dominant antigenic determinants. Of the five 3,6-dideoxyhexoses known to occur naturally, four have been found in various strains of Salmonella enterica (abequose, tyvelose, paratose, and colitose) and all five, including ascarylose, are present among the serotypes of Yersinia pseudotuberculosis. Although there exists one report of the cloning of the rfb region harboring the abequose biosynthetic genes from Y. pseudotuberculosis serogroup HA, the detailed genetic principles underlying a 3,6-dideoxyhexose polymorphism in Y. pseudotuberculosis have not been addressed. To extend the available information on the genes responsible for 3,6-dideoxyhexose formation in Yersinia spp. and facilitate a comparison with the established rfb (O antigen) cluster of Salmonella spp., we report the production of three overlapping clones containing the entire gene cluster required for CDP-ascarylose biosynthesis. On the basis of a detailed sequence analysis, the implications regarding 3,6-dideoxyhexose polymorphism among Salmonella and Yersinia spp. are discussed. In addition, the functional cloning of this region has allowed the expression of Ep (alpha-D-glucose cytidylyltransferase), Eod (CDP-D-glucose 4,6-dehydratase), E1 (CDP-6-deoxy-L-threo-D-glycero-4- hexulose-3-dehydrase), E3 (CDP-6-deoxy-delta 3,4-glucoseen reductase), Eep (CDP-3,6-dideoxy-D-glycero-D- glycero-4-hexulose-5-epimerase), and Ered (CDP-3,6-dideoxy-L-glycero-D-glycero-4-hexulose-4-reductase), facilitating future mechanistic studies of this intriguing biosynthetic pathway.
authors.affiliation: Department of Chemistry, University of Minnesota, Minneapolis 55455.
authors.forename: J S
authors.initials: JS
authors.lastname: Thorson
authors.forename: S F
authors.initials: SF
authors.lastname: Lo
authors.forename: O
authors.initials: O
authors.lastname: Ploux
authors.forename: X
authors.initials: X
authors.lastname: He
authors.forename: H W
authors.initials: HW
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D001482:Base Composition; D001483:Base Sequence; D015139:Blotting, Southern; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D015342:DNA Probes; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D005947:Glucose / Q000031:analogs & derivatives / Q000378:metabolism; D006601:Hexoses / Q000096:biosynthesis*; D006836:Hydro-Lyases / Q000096:biosynthesis* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D005810:Multigene Family; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D011110:Polymorphism, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D015183:Restriction Mapping; D012475:Salmonella / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012703:Serotyping; D015011:Yersinia pseudotuberculosis / Q000145:classification / Q000235:genetics* / Q000378:metabolism*
chemical_list: D015342:DNA Probes; D004269:DNA, Bacterial; D006601:Hexoses; D009702:Nucleoside Diphosphate Sugars; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; C073881:cytidine diphosphate-glucose; C009616:tyvelose; D006836:Hydro-Lyases; C089119:CDP-glucose 4,6-dehydratase; D005947:Glucose