title: Human ISPD Is a Cytidyltransferase Required for Dystroglycan O-Mannosylation.
abstract: A unique, unsolved O-mannosyl glycan on α-dystroglycan is essential for its interaction with protein ligands in the extracellular matrix. Defective O-mannosylation leads to a group of muscular dystrophies, called dystroglycanopathies. Mutations in isoprenoid synthase domain containing (ISPD) represent the second most common cause of these disorders, however, its molecular function remains uncharacterized. The human ISPD (hISPD) crystal structure showed a canonical N-terminal cytidyltransferase domain linked to a C-terminal domain that is absent in cytidyltransferase homologs. Functional studies demonstrated cytosolic localization of hISPD, and cytidyltransferase activity toward pentose phosphates, including ribulose 5-phosphate, ribose 5-phosphate, and ribitol 5-phosphate. Identity of the CDP sugars was confirmed by liquid chromatography quadrupole time-of-flight mass spectrometry and two-dimensional nuclear magnetic resonance spectroscopy. Our combined results indicate that hISPD is a cytidyltransferase, suggesting the presence of a novel human nucleotide sugar essential for functional α-dystroglycan O-mannosylation in muscle and brain. Thereby, ISPD deficiency can be added to the growing list of tertiary dystroglycanopathies.
authors.affiliation: Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Moniek
authors.initials: M
authors.lastname: Riemersma
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK.
authors.forename: D Sean
authors.initials: DS
authors.lastname: Froese
authors.affiliation: Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Walinka
authors.initials: W
authors.lastname: van Tol
authors.affiliation: Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Udo F
authors.initials: UF
authors.lastname: Engelke
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Kopec
authors.affiliation: Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: van Scherpenzeel
authors.affiliation: Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Angel
authors.initials: A
authors.lastname: Ashikov
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK.
authors.forename: Tobias
authors.initials: T
authors.lastname: Krojer
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK.
authors.forename: Frank
authors.initials: F
authors.lastname: von Delft
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, 6525 ED Nijmegen, the Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: Tessari
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego Street, 02-106 Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Buczkowska
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego Street, 02-106 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Swiezewska
authors.affiliation: Netherlands Cancer Institute, 1066 CX Amsterdam, the Netherlands.
authors.forename: Lucas T
authors.initials: LT
authors.lastname: Jae
authors.affiliation: Netherlands Cancer Institute, 1066 CX Amsterdam, the Netherlands.
authors.forename: Thijn R
authors.initials: TR
authors.lastname: Brummelkamp
authors.affiliation: Molecular Glycobiology, Research Team for Mechanisms of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo 173-0015, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Manya
authors.affiliation: Molecular Glycobiology, Research Team for Mechanisms of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo 173-0015, Japan.
authors.forename: Tamao
authors.initials: T
authors.lastname: Endo
authors.affiliation: Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: van Bokhoven
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK. Electronic address: wyatt.yue@sgc.ox.ac.uk.
authors.forename: Wyatt W
authors.initials: WW
authors.lastname: Yue
authors.affiliation: Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands. Electronic address: dirk.lefeber@radboudumc.nl.
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Lefeber
mesh_terms: D002478:Cells, Cultured; D019916:Choline-Phosphate Cytidylyltransferase / Q000737:chemistry; D018360:Crystallography, X-Ray; D049030:Dystroglycans / Q000737:chemistry / Q000378:metabolism*; D005347:Fibroblasts; D055786:Gene Knockout Techniques; D006031:Glycosylation; D006801:Humans; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D049030:Dystroglycans; D009713:Nucleotidyltransferases; D019916:Choline-Phosphate Cytidylyltransferase; C573136:CRPPA protein, human