RRC ID 33947
Author Olson LJ, Orsi R, Peterson FC, Parodi AJ, Kim JJ, D'Alessio C, Dahms NM.
Title Crystal Structure and Functional Analyses of the Lectin Domain of Glucosidase II: Insights into Oligomannose Recognition.
Journal Biochemistry
Abstract N-Glycans are modified as part of a quality control mechanism during glycoprotein folding in the endoplasmic reticulum (ER). Glucosidase II (GII) plays a critical role by generating monoglucosylated glycans that are recognized by lectin chaperones, calnexin and calreticulin. To understand how the hydrolytic activity of GIIα is enhanced by the mannose 6-phosphate receptor (MPR) homology domain (MRH domain) of its β subunit, we now report a 1.6 Å resolution crystal structure of the MRH domain of GIIβ bound to mannose. A comparison of ligand-bound and unbound structures reveals no major difference in their overall fold, but rather a repositioning of side chains throughout the binding pocket, including Y372. Mutation of Y372 inhibits GII activity, demonstrating an important role for Y372 in regulating GII activity. Comparison of the MRH domains of GIIβ, MPRs, and the ER lectin OS-9 identified conserved residues that are critical for the structural integrity and architecture of the carbohydrate binding pocket. As shown by nuclear magnetic resonance spectroscopy, mutations of the primary binding pocket residues and adjacent W409, all of which inhibit the activity of GII both in vitro and in vivo, do not cause a significant change in the overall fold of the GIIβ MRH domain but impact locally the stability of the binding pocket. W409 does not directly contact mannose; rather, its indole ring is stabilized by binding into a hydrophobic pocket of an adjacent crystallographic neighbor. This suggests that W409 interacts with a hydrophobic region of the GIIβ or GIIα subunit to modulate its effect on GII activity.
Volume 54(26)
Pages 4097-111
Published 2015-7-7
DOI 10.1021/acs.biochem.5b00256
PMID 26062005
PMC PMC6202027
MeSH Amino Acid Sequence Animals Crystallography, X-Ray Humans Lectins / metabolism* Mannose / metabolism* Models, Molecular Molecular Sequence Data Point Mutation Protein Structure, Tertiary Protein Subunits / chemistry Protein Subunits / genetics Protein Subunits / metabolism Receptor, IGF Type 2 / metabolism Schizosaccharomyces / chemistry Schizosaccharomyces / enzymology* Schizosaccharomyces / genetics Schizosaccharomyces / metabolism Sequence Alignment alpha-Glucosidases / chemistry* alpha-Glucosidases / genetics alpha-Glucosidases / metabolism*
IF 2.865
Times Cited 8
DNA material S. pombe entry SpEnt26D11 (SPW010483)