title: Non-lysosomal Degradation of Singly Phosphorylated Oligosaccharides Initiated by the Action of a Cytosolic Endo-β-N-acetylglucosaminidase.
abstract: Phosphorylated oligosaccharides (POSs) are produced by the degradation of dolichol-linked oligosaccharides (DLOs) by an unclarified mechanism in mammalian cells. Although POSs are exclusively found in the cytosol, their intracellular fates remain unclear. Our findings indicate that POSs are catabolized via a non-lysosomal glycan degradation pathway that involves a cytosolic endo-β-N-acetylglucosaminidase (ENGase). Quantitative and structural analyses of POSs revealed that ablation of the ENGase results in the significant accumulation of POSs with a hexasaccharide structure composed of Manα1,2Manα1,3(Manα1,6)Manβ1,4GlcNAcβ1,4GlcNAc.In vitroENGase assays revealed that the presence of an α1,2-linked mannose residue facilitates the hydrolysis of POSs by the ENGase. Liquid chromatography-mass spectrometric analyses and fluorescent labeling experiments show that such POSs contain one phosphate group at the reducing end. These results indicate that ENGase efficiently hydrolyzes POSs that are larger than Man4GlcNAc2-P, generating GlcNAc-1-P and neutral Gn1-type free oligosaccharides. These results provide insight into important aspects of the generation and degradation of POSs.
authors: From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198.
authors: Yoichiro
authors: Y
authors: Harada
authors: From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198.
authors: Chengcheng
authors: C
authors: Huang
authors: the Global Application Development Center, Analytical and Measuring Instruments Division, Shimadzu Corp., Hadano, Kanagawa 259-1304, and.
authors: Satoshi
authors: S
authors: Yamaki
authors: the Collaboration Promotion Unit, RIKEN Global Research Cluster, Wako, Saitama 351-0198, Japan.
authors: Naoshi
authors: N
authors: Dohmae
authors: From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, tsuzuki_gm@riken.jp.
authors: Tadashi
authors: T
authors: Suzuki
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D006868:Hydrolysis; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D009844:Oligosaccharides; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
keywords: N-linked glycosylation; carbohydrate metabolism; dolichol-linked oligosaccharides; endo-β-N-acetylglucosaminidase; endoplasmic reticulum (ER); glycobiology; non-lysosomal glycan degradation; oligosaccharide; phosphorylated oligosaccharides