Binding of the dystrophin second repeat to membrane di-oleyl phospholipids is dependent upon lipid packing.
Dystrophin is the genetically deficient protein in Duchenne Muscular Dystrophy. Its C- and N-terminal ends interact with cytoskeletal and membrane proteins, establishing a link between the cytoskeleton and the extracellular matrix. In a previous study, we showed that there is an interaction between the second repeat of the rod domain and membrane phospholipids, which places tryptophan residues in close contact with the membrane. Here, we examine the binding of the dystrophin repeat-2 to small unilamellar vesicles with varying composition. We find that the protein binds predominantly to di-oleyl-phosphatidylserine. The binding as a function of increasing mol% of DOPS appears to be cooperative due to reduction of dimensionality, greatly enhanced in the absence of salts, and partly modulated by pH. Substituting small by large unilamellar vesicles induces a 30-fold lower affinity of the protein for the membrane phospholipids. However, modifying the packing of the acyl chains by introducing lipids such as phosphatidylethanolamine and cholesterol to the vesicle leads to an approximately 7-fold increase in affinity. Taken together, these results show that the binding involves electrostatic forces in addition to hydrophobic ones.
Le Rumeur
Elisabeth
E
UMR CNRS 6026 - IFR 140, Equipe RMN-Interactions lipides protéines, Faculté de Médecine, Université de Rennes 1, CS 34317, 35043 Rennes cedex, France. elisabeth.lerumeur@univ-rennes1.fr
Pottier
Sandrine
S
Da Costa
Gregory
G
Metzinger
Laurent
L
Mouret
Liza
L
Rocher
Chantal
C
Fourage
Marie
M
Rondeau-Mouro
Corinne
C
Bondon
Arnaud
A
D016189:Dystrophin / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008027:Light; D008563:Membrane Lipids / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D020449:Repetitive Sequences, Amino Acid; D012542:Scattering, Radiation; D055672:Static Electricity; D053835:Unilamellar Liposomes / Q000737:chemistry
D016189:Dystrophin; D008563:Membrane Lipids; D010743:Phospholipids; D053835:Unilamellar Liposomes