Crystal structures of fukutin-related protein (FKRP), a ribitol-phosphate transferase related to muscular dystrophy

  • Nat Commun. 2020 Jan 16;11(1):303. doi: 10.1038/s41467-019-14220-z.
Naoyuki Kuwabara  #  1 ,  Rieko Imae  #  2 ,  Hiroshi Manya  2 ,  Tomohiro Tanaka  3 ,  Mamoru Mizuno  3 ,  Hiroki Tsumoto  4 ,  Motoi Kanagawa  5 ,  Kazuhiro Kobayashi  5 ,  Tatsushi Toda  5  6 ,  Toshiya Senda  1  7 ,  Tamao Endo  8 ,  Ryuichi Kato  9  10
Affiliations
  • 1. Structural Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan.
  • 2. Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan.
  • 3. Laboratory of Glyco-organic Chemistry, The Noguchi Institute, Itabashi-ku, Tokyo, 173-0003, Japan.
  • 4. Proteome Research, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan.
  • 5. Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Hyogo, 650-0017, Japan.
  • 6. Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
  • 7. School of High Energy Accelerator Science, SOKENDAI, Tsukuba, Ibaraki, 305-0801, Japan.
  • 8. Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan. [email protected].
  • 9. Structural Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan. [email protected].
  • 10. School of High Energy Accelerator Science, SOKENDAI, Tsukuba, Ibaraki, 305-0801, Japan. [email protected].
  • # Contributed equally.
PMID: 31949166 DOI: 10.1038/s41467-019-14220-z
Abstract

α-Dystroglycan (α-DG) is a highly-glycosylated surface membrane protein. Defects in the O-mannosyl glycan of α-DG cause dystroglycanopathy, a group of congenital muscular dystrophies. The core M3 O-mannosyl glycan contains tandem ribitol-phosphate (RboP), a characteristic feature first found in mammals. Fukutin and fukutin-related protein (FKRP), whose mutated genes underlie dystroglycanopathy, sequentially transfer RboP from cytidine diphosphate-ribitol (CDP-Rbo) to form a tandem RboP unit in the core M3 glycan. Here, we report a series of crystal structures of FKRP with and without donor (CDP-Rbo) and/or acceptor [RboP-(phospho-)core M3 peptide] substrates. FKRP has N-terminal stem and C-terminal catalytic domains, and forms a tetramer both in crystal and in solution. In the acceptor complex, the phosphate group of RboP is recognized by the catalytic domain of one subunit, and a phosphate group on O-mannose is recognized by the stem domain of another subunit. Structure-based functional studies confirmed that the dimeric structure is essential for FKRP enzymatic activity.