Synthesis of Glc₁Man₉‐Glycoprotein Probes by a Misfolding/Enzymatic Glucosylation/Misfolding Sequence

Abstract

Glycoproteins in non-native conformations are often toxic to cells and may cause diseases,t hus the quality control (QC) system eliminates these unwanted species.Lectin chaperone calreticulin and glucosidase II, both of which recognizet he Glc 1 Man 9 oligosaccharide on glycoproteins,a re important components of the glycoprotein QC system. Reported herein is the preparation of Glc 1 Man 9 -glycoproteins in both native and non-native conformations by using the following sequence:m isfolding of chemically synthesized Man 9 -glycoprotein, enzymatic glucosylation, and another misfolding step.B yu sing synthetic glycoprotein probes, calreticulin was found to bind preferentially to ahydrophobic non-native glycoprotein whereas glucosidase II activity was not affected by glycoprotein conformation. The results demonstrate the ability of chemical synthesis to deliver homogeneous glycoproteins in several non-native conformations for probing the glycoprotein QC system.

Clamping, Bending, and Twisting Inter-Domain Motions in the Misfold-Recognising Portion of UDP-Glucose: Glycoprotein Glucosyl-Transferase

“…Since the discovery of UGGT in 1989 (Parodi, 2007;Trombetta et al, 1989), UGGT activity studies have used a range of glycoprotein substrates (Trombetta et al, 1989;Taylor et al, 2004;Ritter and Helenius, 2000;Ritter et al, 2005), small-size glycosylated synthetic compounds (Totani et al, 2006(Totani et al, , 2009, and chemically synthesized misfolded glycoproteins (Izumi et al, 2016a(Izumi et al, , 2016bKiuchi et al, 2018). In addition to glycoprotein monomers, UGGT also surveys the quaternary structure of glycoprotein oligomers and larger multi-glycoprotein complexes (Keith et al, 2005;Zhang et al, 2011;Gardner and Kearse, 1999).…”