The micelle to vesicle transition of lipids and detergents in the presence of a membrane protein: towards a rationale for 2D crystallization.
The assembly of two-dimensional membrane protein crystals in the presence of lipids was analyzed with quasielastic light scattering and electron microscopy. Mixtures of detergent-solubilized lipids and/or proteins were submitted to slow or rapid dilution while measuring the hydrodynamic radii of the aggregates. Lipids alone exhibited lambda-shaped dilution curves with intermediate rod-shaped particles that converted into small vesicles. Depending on the protein-protein and protein-lipid interactions, detergent-solubilized protein-lipid mixtures showed a sharp transition from micelles to large densely packed proteoliposomes. Electron microscopy revealed that formation of crystals occurred shortly after this phase transition.
Dolder
M
M
Institute of Cell Biology, ETH, Zürich, Switzerland.
Engel
A
A
Zulauf
M
M
D003460:Crystallization; D003902:Detergents / Q000737:chemistry*; D006801:Humans; D007834:Lasers; D008027:Light; D008565:Membrane Proteins / Q000737:chemistry*; D008823:Micelles; D010713:Phosphatidylcholines / Q000737:chemistry*; D011510:Proteolipids / Q000648:ultrastructure; D012542:Scattering, Radiation
D003902:Detergents; D008565:Membrane Proteins; D008823:Micelles; D010713:Phosphatidylcholines; D011510:Proteolipids; C020485:proteoliposomes