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

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

1 Department of Biomedical 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 carboxy-terminal cysteine-rich regions, comprising WW, EF hand and ZZ domains. The EF hand region stabilises the WW domain providing the main interaction site between dystrophin or utrophin and dystroglycan. The ZZ domain, containing a predicted zinc finger motif, stabilises 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 localised to the conformationaly sensitive second zinc binding site in the ZZ domain. Our results suggest that residues 3326-3332 of dystrophin, forms a crucial part of the contact region between dystrophin and {beta}-dystroglycan and provides new insight into ZZ domain organisation and function.

Mots clés: Life Sciences

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, 2006, 401 (3), pp.667-677. ⟨10.1042/BJ20061051⟩. ⟨hal-00478628⟩