title: Fbs1 protects the malfolded glycoproteins from the attack of peptide:N-glycanase.
abstract: Fbs1 is a cytosolic lectin putatively operating as a chaperone as well as a substrate-recognition subunit of the SCF(Fbs1) ubiquitin ligase complex. To provide structural and functional basis of preferential binding of Fbs1 to unfolded glycoproteins, we herein characterize the interaction of Fbs1 with a heptapeptide carrying Man3GlcNAc2 by nuclear magnetic resonance (NMR) spectroscopy and other biochemical methods. Inspection of the NMR data obtained by use of the isotopically labeled glycopeptide indicated that Fbs1 interacts with sugar-peptide junctions, which are shielded in native glycoprotein, in many cases, but become accessible to Fbs1 in unfolded glycoproteins. Furthermore, Fbs1 was shown to inhibit deglycosylation of denatured ribonuclease B by a cytosolic peptide:N-glycanase (PNGase). On the basis of these data, we suggest that Fbs1 captures malfolded glycoproteins, protecting them from the attack of PNGase, during the chaperoning or ubiquitinating operation in the cytosol.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Nagoya 467-8603, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hirao
authors.forename: Eri
authors.initials: E
authors.lastname: Sakata
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Eiji
authors.initials: E
authors.lastname: Kurimoto
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Koichi
authors.initials: K
authors.lastname: Kato
mesh_terms: D018797:Cell Cycle Proteins / Q000737:chemistry / Q000502:physiology*; D044783:F-Box Proteins; D005982:Glutathione Transferase / Q000378:metabolism; D006020:Glycopeptides / Q000737:chemistry; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000737:chemistry* / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D012260:Ribonucleases / Q000737:chemistry; D013379:Substrate Specificity; D020349:Surface Plasmon Resonance; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry
chemical_list: D018797:Cell Cycle Proteins; D044783:F-Box Proteins; C485508:FBXO2 protein, human; D006020:Glycopeptides; D037102:Lectins; D009419:Nerve Tissue Proteins; D010455:Peptides; D011134:Polysaccharides; D044767:Ubiquitin-Protein Ligases; D005982:Glutathione Transferase; D012260:Ribonucleases; C029600:ribonuclease B; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase