Browsing by Subject "Glycosyltransferases"

Now showing 1 - 1 of 1
  • Thumbnail Image
    ItemOpen Access
    Structure of the polyisoprenyl-phosphate glycosyltransferase GtrB and insights into the mechanism of catalysis.
    (Nat Commun, 2016-01-05) Ardiccioni, Chiara; Clarke, Oliver B; Tomasek, David; Issa, Habon A; von Alpen, Desiree C; Pond, Heather L; Banerjee, Surajit; Rajashankar, Kanagalaghatta R; Liu, Qun; Guan, Ziqiang; Li, Chijun; Kloss, Brian; Bruni, Renato; Kloppmann, Edda; Rost, Burkhard; Manzini, M Chiara; Shapiro, Lawrence; Mancia, Filippo
    The attachment of a sugar to a hydrophobic polyisoprenyl carrier is the first step for all extracellular glycosylation processes. The enzymes that perform these reactions, polyisoprenyl-glycosyltransferases (PI-GTs) include dolichol phosphate mannose synthase (DPMS), which generates the mannose donor for glycosylation in the endoplasmic reticulum. Here we report the 3.0 Å resolution crystal structure of GtrB, a glucose-specific PI-GT from Synechocystis, showing a tetramer in which each protomer contributes two helices to a membrane-spanning bundle. The active site is 15 Å from the membrane, raising the question of how water-soluble and membrane-embedded substrates are brought into apposition for catalysis. A conserved juxtamembrane domain harbours disease mutations, which compromised activity in GtrB in vitro and in human DPM1 tested in zebrafish. We hypothesize a role of this domain in shielding the polyisoprenyl-phosphate for transport to the active site. Our results reveal the basis of PI-GT function, and provide a potential molecular explanation for DPM1-related disease.