6RY6 image
Entry Detail
PDB ID:
6RY6
Keywords:
Title:
Crystal structure of Dfg5 from Chaetomium thermophilum in complex with glucosamine
Biological Source:
PDB Version:
Deposition Date:
2019-06-10
Release Date:
2020-08-12
Method Details:
Experimental Method:
Resolution:
1.30 Å
R-Value Free:
0.12
R-Value Work:
0.11
R-Value Observed:
0.11
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Mannan endo-1,6-alpha-mannosidase
Chain IDs:A
Chain Length:443
Number of Molecules:1
Biological Source:Chaetomium thermophilum var. thermophilum DSM 1495
Primary Citation
Structural base for the transfer of GPI-anchored glycoproteins into fungal cell walls.
Proc.Natl.Acad.Sci.USA 117 22061 22067 (2020)
PMID: 32839341 DOI: 10.1073/pnas.2010661117

Abstact

The correct distribution and trafficking of proteins are essential for all organisms. Eukaryotes evolved a sophisticated trafficking system which allows proteins to reach their destination within highly compartmentalized cells. One eukaryotic hallmark is the attachment of a glycosylphosphatidylinositol (GPI) anchor to C-terminal ω-peptides, which are used as a zip code to guide a subset of membrane-anchored proteins through the secretory pathway to the plasma membrane. In fungi, the final destination of many GPI-anchored proteins is their outermost compartment, the cell wall. Enzymes of the Dfg5 subfamily catalyze the essential transfer of GPI-anchored substrates from the plasma membrane to the cell wall and discriminate between plasma membrane-resident GPI-anchored proteins and those transferred to the cell wall (GPI-CWP). We solved the structure of Dfg5 from a filamentous fungus and used in crystallo glycan fragment screening to reassemble the GPI-core glycan in a U-shaped conformation within its binding pocket. The resulting model of the membrane-bound Dfg5•GPI-CWP complex is validated by molecular dynamics (MD) simulations and in vivo mutants in yeast. The latter show that impaired transfer of GPI-CWPs causes distorted cell-wall integrity as indicated by increased chitin levels. The structure of a Dfg5•β1,3-glycoside complex predicts transfer of GPI-CWP toward the nonreducing ends of acceptor glycans in the cell wall. In addition to our molecular model for Dfg5-mediated transglycosylation, we provide a rationale for how GPI-CWPs are specifically sorted toward the cell wall by using GPI-core glycan modifications.

Legend

Protein

Chemical

Disease

Primary Citation of related structures