title: Interaction of dystrophin rod domain with membrane phospholipids. Evidence of a close proximity between tryptophan residues and lipids.
abstract: Dystrophin is assumed to act via the central rod domain as a flexible linker between the amino-terminal actin binding domain and carboxyl-terminal proteins associated with the membrane. The rod domain is made up of 24 spectrin-like repeats and has been shown to modify the physical properties of lipid membranes. The nature of this association still remains unclear. Tryptophan residues tend to cluster at or near to the water-lipid interface of the membrane. To assess dystrophin rod domain-membrane interactions, tryptophan residues properties of two recombinant proteins of the rod domain were examined by (1)H NMR and fluorescence techniques in the presence of membrane lipids. F114 (residues 439-553) is a partly folded protein as inferred from (1)H NMR, tryptophan fluorescence emission intensity, and the excited state lifetime. By contrast, F125 (residues 439-564) is a folded compact protein. Tryptophan fluorescence quenching shows that both proteins are characterized by structural fluctuations with their tryptophan residues only slightly buried from the surface. In the presence of negatively charged small vesicles, the fluorescence characteristics of F125 change dramatically, indicating that tryptophan residues are in a more hydrophobic environment. Interestingly, these modifications are not observed with F114. Fluorescence quenching experiments confirm that tryptophan residues are shielded from the solvent in the complex F125 lipids by a close contact with lipids. The use of membrane-bound quenchers allowed us to conclude that dystrophin rod domain lies along the membrane surface and may be involved in a structural array comprising membrane and cytoskeletal proteins as well as membrane lipids.
authors.affiliation: Laboratoire de Résonance Magnétique Nucléaire en Biologie et Médecine, Unité Propre de Recherche de l'Enseignement Supérieur EA 2230, Faculté de Médecine, CS 34317, Rennes 35043 cedex, France. elisabeth.lerumeur@univ-rennes1.fr
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Le Rumeur
authors.forename: Yann
authors.initials: Y
authors.lastname: Fichou
authors.forename: Sandrine
authors.initials: S
authors.lastname: Pottier
authors.forename: François
authors.initials: F
authors.lastname: Gaboriau
authors.forename: Corinne
authors.initials: C
authors.lastname: Rondeau-Mouro
authors.forename: Michel
authors.initials: M
authors.lastname: Vincent
authors.forename: Jacques
authors.initials: J
authors.lastname: Gallay
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bondon
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D016189:Dystrophin / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D014364:Tryptophan
chemical_list: D016189:Dystrophin; D008563:Membrane Lipids; D010743:Phospholipids; D014364:Tryptophan