ZZ domain of dystrophin and utrophin: topology and mapping of a beta-dystroglycan interaction site.

Karim Hnia (1, 2) , Dora Zouiten (2) , Sonia Cantel (3) , Delphine Chazalette (1) , Gérald Hugon (1) , Jean-Alain Fehrentz (3) , Ahmed Masmoudi (2) , Ann Diment (4) , Janice Bramham (4) , Dominique Mornet (1) , Steve J. Winder (5)

1 Muscle et pathologies
2 Institut Supérieur de Biotechnologie & Unité de recherche 08/39
3 LAPP - Laboratoire des Amino-acides Peptides et Protéines
4 Institute of Cell and Molecular Biology
5 Department of Biochemical Science

Dystrophin forms part of a vital link between actin cytoskeleton and extracellular matrix via the transmembrane adhesion receptor dystroglycan. Dystrophin and its autosomal homologue utrophin interact with beta-dystroglycan via their highly conserved C-terminal cysteine-rich regions, comprising the WW domain (protein-protein interaction domain containing two conserved tryptophan residues), EF hand and ZZ domains. The EF hand region stabilizes the WW domain providing the main interaction site between dystrophin or utrophin and dystroglycan. The ZZ domain, containing a predicted zinc finger motif, stabilizes the WW and EF hand domains and strengthens the overall interaction between dystrophin or utrophin and beta-dystroglycan. Using bacterially expressed ZZ domain, we demonstrate a conformational effect of zinc binding to the ZZ domain, and identify two zinc-binding regions within the ZZ domain by SPOTs overlay assays. Epitope mapping of the dystrophin ZZ domain was carried out with new monoclonal antibodies by ELISA, overlay assay and immunohistochemistry. One monoclonal antibody defined a discrete region of the ZZ domain that interacts with beta-dystroglycan. The epitope was localized to the conformationally sensitive second zinc-binding site in the ZZ domain. Our results suggest that residues 3326-3332 of dystrophin form a crucial part of the contact region between dystrophin and beta-dystroglycan and provide new insight into ZZ domain organization and function.

Mots clés: zinc binding; Duchenne muscular dystrophy; dystroglycan; dystrophin; epitope mapping; utrophin; zinc binding.

Domaines: Biologie cellulaire

Karim Hnia, Dora Zouiten, Sonia Cantel, Delphine Chazalette, Gérald Hugon, et al.. ZZ domain of dystrophin and utrophin: topology and mapping of a beta-dystroglycan interaction site.. Biochemical Journal, 2007, 401 (3), pp.667-77. ⟨10.1042/BJ20061051⟩. ⟨inserm-00144563⟩