title: Discovery of human Golgi β-galactosidase with no identified glycosidase using a QMC substrate design platform for exo-glycosidase.
abstract: Post-translational modifications (PTMs) of proteins play important roles in the physiology of eukaryotes. In the PTMs, non-reversible glycosylations are classified as N-glycosylations and O-glycosylations, and are catalyzed by various glycosidases and glycosyltransferases. However, β-glycosidases are not known to play a role in N- and O-glycan processing, although both glycans provide partial structures as substrates for β-galactosidase and β-N-acetylglucosaminidase in the Golgi apparatus of human cells. We explored human Golgi β-galactosidase using fluorescent substrates based on a quinone methide cleavage (QMC) substrate design platform that was previously developed to image exo-type glycosidases in living cells. As a result, we discovered a novel Golgi β-galactosidase in human cells. It is possible to predict a novel and important function in glycan processing of this β-galactosidase, because various β-galactosyl linkages in N- and O-glycans exist in Golgi apparatus. In addition, these results show that the QMC platform is excellent for imaging exo-type glycosidases.
authors.affiliation: Department of Chemistry and Life Science, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Miura
authors.affiliation: Department of Chemistry and Life Science, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan. Electronic address: hakamata.wataru@nihon-u.ac.jp.
authors.forename: Wataru
authors.initials: W
authors.lastname: Hakamata
authors.affiliation: Department of Chemistry and Life Science, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Department of Chemistry and Life Science, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Hirano
authors.affiliation: Department of Chemistry and Life Science, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nishio
mesh_terms: D045744:Cell Line, Tumor; D005453:Fluorescence; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D006056:Golgi Apparatus / Q000201:enzymology*; D006367:HeLa Cells; D006801:Humans; D045563:Indolequinones / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D001616:beta-Galactosidase / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D045563:Indolequinones; C068040:quinone methide; D006026:Glycoside Hydrolases; D001616:beta-Galactosidase
keywords: Fluorescent imaging; Glycan processing; Golgi apparatus; Post-translational modifications; Quinone methide cleavage; β-Galactosidase