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Hyaluronan synthase assembles chitin oligomers with -GlcNAc(α1→)UDP at the reducing end.
Weigel, Paul H; West, Christopher M; Zhao, Peng; Wells, Lance; Baggenstoss, Bruce A; Washburn, Jennifer L.
Afiliación
  • Weigel PH; Department of Biochemistry and Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA paul-weigel@ouhsc.edu.
  • West CM; Department of Biochemistry and Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
  • Zhao P; Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712, USA.
  • Wells L; Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712, USA.
  • Baggenstoss BA; Department of Biochemistry and Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
  • Washburn JL; Department of Biochemistry and Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
Glycobiology ; 25(6): 632-43, 2015 Jun.
Article en En | MEDLINE | ID: mdl-25583822
Class I hyaluronan synthases (HASs) assemble a polysaccharide containing the repeating disaccharide [GlcNAc(ß1,4)GlcUA(ß1,3)]n-UDP and vertebrate HASs also assemble (GlcNAc-ß1,4)n homo-oligomers (chitin) in the absence of GlcUA-UDP. This multi-membrane domain CAZy GT2 family glycosyltransferase, which couples HA synthesis and translocation across the cell membrane, is atypical in that monosaccharides are incrementally assembled at the reducing, rather than the non-reducing, end of the growing polymer. Using Escherichia coli membranes containing recombinant Streptococcus equisimilis HAS, we demonstrate that a prokaryotic Class I HAS also synthesizes chitin oligomers (up to 15-mers, based on MS and MS/MS analyses of permethylated products). Furthermore, chitin oligomers were found attached at their reducing end to -4GlcNAc(α1→)UDP [i.e. (GlcNAcß1,4)nGlcNAc(α1→)UDP]. These oligomers, which contained up to at least seven HexNAc residues, consisted of ß4-linked GlcNAc residues, based on the sensitivity of the native products to jack bean ß-N-acetylhexosaminidase. Interestingly, these oligomers exhibited mass defects of -2, or -4 for longer oligomers, that strictly depended on conjugation to UDP, but MS/MS analyses indicate that these species result from chemical dehydrogenations occurring in the gas phase. Identification of (GlcNAc-ß1,4)n-GlcNAc(α1→)UDP as HAS reaction products, made in the presence of GlcNAc(α1→)UDP only, provides strong independent confirmation for the reducing terminal addition mechanism. We conclude that chitin oligomer products made by HAS are derived from the cleavage of these novel activated oligo-chitosyl-UDP oligomers. Furthermore, it is possible that these UDP-activated chitin oligomers could serve as self-assembled primers for initiating HA synthesis and ultimately modify the non-reducing terminus of HA with a chitin cap.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Acetilglucosamina / Uridina Difosfato / Quitina / Glucuronosiltransferasa Idioma: En Revista: Glycobiology Asunto de la revista: BIOQUIMICA Año: 2015 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido
Texto completo
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Acetilglucosamina / Uridina Difosfato / Quitina / Glucuronosiltransferasa Idioma: En Revista: Glycobiology Asunto de la revista: BIOQUIMICA Año: 2015 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido