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Structure Of The Polyisoprenyl-Phosphate Glycosyltransferase Gtrb And Insights Into The Mechanism Of Catalysis, Chiara Ardiccioni, Oliver B. Clarke, David Tomasek, Habon A. Issa, Desiree C. Von Alpen, Heather L. Pond, M. Chiara Manzini, +11 Additional Authors

Pharmacology and Physiology Faculty Publications

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 3.0Å 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 …