Conformational states and thermodynamics of alpha-lactalbumin bound to membranes: a case study of the effects of pH, calcium, lipid membrane curvature and charge.
The study of the conformational changes of bovine alpha-lactalbumin, switching from soluble states to membrane-bound states, deepens our knowledge of the behaviour of amphitropic proteins. The binding and the membrane-bound conformations of alpha-lactalbumin are highly sensitive to environmental factors, like calcium and proton concentrations, curvature and charge of the lipid membrane. The interactions between the protein and the membrane result from a combination of hydrophobic and electrostatic interactions and the respective weights of these interactions depend on the physicochemical conditions. As inferred by macroscopic as well as residue-level methods, the conformations of the membrane-bound protein range from native-like to molten globule-like states. However, the regions anchoring the protein to the membrane are similar and restricted to amphiphilic alpha-helices. H/(2)H-exchange experiments also yield residue-level data that constitute comprehensive information providing a new point of view on the thermodynamics of the interactions between the protein and the membrane.
Chenal
Alexandre
A
Biophysique Moléculaire et Cellulaire, Unité Mixte de Recherche 5090, Département Réponse et Dynamique Cellulaires, CEA-Grenoble, 38054 Grenoble cedex 9, France. chenal@dsvidf.cea.fr
Vernier
Grégory
G
Savarin
Philippe
P
Bushmarina
Natalia A
NA
Gèze
Annabelle
A
Guillain
Florent
F
Gillet
Daniel
D
Forge
Vincent
V
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D002942:Circular Dichroism; D041961:Deuterium Exchange Measurement; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007768:Lactalbumin / Q000737:chemistry* / Q000378:metabolism*; D050356:Lipid Metabolism; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D055672:Static Electricity; D013816:Thermodynamics
D008081:Liposomes; D007768:Lactalbumin; D002118:Calcium