Degradation pathway of plant complex-type N-glycans: identification and characterization of a key α1,3-fucosidase from glycoside hydrolase family 29

Biochem J. 2018 Jan 11;475(1):305-317. doi: 10.1042/BCJ20170106.

Abstract

Plant complex-type N-glycans are characterized by the presence of α1,3-linked fucose towards the proximal N-acetylglucosamine residue and β1,2-linked xylose towards the β-mannose residue. These glycans are ultimately degraded by the activity of several glycoside hydrolases. However, the degradation pathway of plant complex-type N-glycans has not been entirely elucidated because the gene encoding α1,3-fucosidase, a glycoside hydrolase acting on plant complex-type N-glycans, has not yet been identified, and its substrate specificity remains to be determined. In the present study, we found that AtFUC1 (an Arabidopsis GH29 α-fucosidase) is an α1,3-fucosidase acting on plant complex-type N-glycans. This fucosidase has been known to act on α1,4-fucoside linkage in the Lewis A epitope of plant complex-type N-glycans. We found that this glycoside hydrolase specifically acted on GlcNAcβ1-4(Fucα1-3)GlcNAc, a degradation product of plant complex-type N-glycans, by sequential actions of vacuolar α-mannosidase, β1,2-xylosidase, and endo-β-mannosidase. The AtFUC1-deficient mutant showed no distinct phenotypic plant growth features; however, it accumulated GlcNAcβ1-4(Fucα1-3)GlcNAc, a substrate of AtFUC1. These results showed that AtFUC1 is an α1,3-fucosidase acting on plant complex-type N-glycans and elucidated the degradation pathway of plant complex-type N-glycans.

Keywords: N-glycan; fucosidase; glycobiology; glycoside hydrolase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylglucosamine / chemistry
  • Acetylglucosamine / metabolism
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Carbohydrate Sequence
  • Cloning, Molecular
  • Fucose / chemistry
  • Fucose / metabolism
  • Gene Expression
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism
  • Mannose / chemistry
  • Mannose / metabolism
  • Pichia / genetics
  • Pichia / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Polysaccharides / chemistry*
  • Polysaccharides / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Substrate Specificity
  • Xylose / chemistry
  • Xylose / metabolism
  • alpha-L-Fucosidase / genetics
  • alpha-L-Fucosidase / metabolism*

Substances

  • Plant Proteins
  • Polysaccharides
  • Recombinant Proteins
  • Fucose
  • Xylose
  • alpha-L-Fucosidase
  • Mannose
  • Acetylglucosamine