title: Dystrophin Hot-Spot Mutants Leading to Becker Muscular Dystrophy Insert More Deeply into Membrane Models than the Native Protein.
abstract: Dystrophin (DYS) is a membrane skeleton protein whose mutations lead to lethal Duchenne muscular dystrophy or to the milder Becker muscular dystrophy (BMD). One third of BMD "in-frame" exon deletions are located in the region that codes for spectrin-like repeats R16 to R21. We focused on four prevalent mutated proteins deleted in this area (called RΔ45-47, RΔ45-48, RΔ45-49, and RΔ45-51 according to the deleted exon numbers), analyzing protein/membrane interactions. Two of the mutants, RΔ45-48 and RΔ45-51, led to mild pathologies and displayed a similar triple coiled-coil structure as the full-length DYS R16-21, whereas the two others, RΔ45-47 and RΔ45-49, induced more severe pathologies and showed "fractional" structures unrelated to the normal one. To explore lipid packing, small unilamellar liposomes (SUVs) and planar monolayers were used at various initial surface pressures. The dissociation constants determined by microscale thermophoresis (MST) were much higher for the full-length DYS R161-21 than for the mutants; thus the wild type protein has weaker SUV binding. Comparing surface pressures after protein adsorption and analysis of atomic force microscopy images of mixed protein/lipid monolayers revealed that the mutants insert more into the lipid monolayer than the wild type does. In fact, in both models every deletion mutant showed more interactions with membranes than the full-length protein did. This means that mutations in the R16-21 part of dystrophin disturb the protein's molecular behavior as it relates to membranes, regardless of whether the accompanying pathology is mild or severe.
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6251, Institut de Physique de Rennes, 35042 Rennes, France.|UMR CNRS 6290, Équipe SIM, 35043 Rennes, France.
authors.forename: Sarah
authors.initials: S
authors.lastname: Ameziane-Le Hir
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6251, Institut de Physique de Rennes, 35042 Rennes, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Paboeuf
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6290, Équipe SIM, 35043 Rennes, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Tascon
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6290, Équipe SIM, 35043 Rennes, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Hubert
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6290, Équipe SIM, 35043 Rennes, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Le Rumeur
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6251, Institut de Physique de Rennes, 35042 Rennes, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Vié
authors.affiliation: Université de Rennes 1 , 35042 Rennes, France.|UMR CNRS 6290, Équipe SIM, 35043 Rennes, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Raguénès-Nicol
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D016189:Dystrophin / Q000737:chemistry* / Q000235:genetics*; D005091:Exons; D006801:Humans; D008563:Membrane Lipids / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics* / Q000378:metabolism*; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics*; D009154:Mutation; D020449:Repetitive Sequences, Amino Acid; D017384:Sequence Deletion; D013049:Spectrin / Q000737:chemistry / Q000235:genetics; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: C484258:DMD protein, human; D016189:Dystrophin; D008563:Membrane Lipids; D050505:Mutant Proteins; D053835:Unilamellar Liposomes; D013049:Spectrin