Bacteriorhodopsin/Amphipol Complexes: Structural and Functional Properties

• Published in: Biophysical journal 2008-05, Vol.94 (9), p.3523-3537
• Main Authors: Gohon, Yann, Dahmane, Tassadite, Ruigrok, Rob W.H., Schuck, Peter, Charvolin, Delphine, Rappaport, Fabrice, Timmins, Peter, Engelman, Donald M., Tribet, Christophe, Popot, Jean-Luc, Ebel, Christine
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Bacteriorhodopsin; Bacteriorhodopsins - chemistry; Bacteriorhodopsins - metabolism; Chromatography, Gel; Colloids - chemistry; Color; Detergents; Halobacterium salinarum - metabolism; Kinetics; Lipids; Lipids - chemistry; Membranes; Microscopy; Microscopy, Electron; Monomers; Neutron Diffraction; Polymers; Polymers - chemistry; Polymers - metabolism; Propylamines - chemistry; Propylamines - metabolism; Protein Structure, Secondary; Proteins; Purple Membrane - chemistry; Purple Membrane - metabolism; Scattering, Small Angle; Thioglucosides - chemistry; Ultracentrifugation
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1529/biophysj.107.121848

The membrane protein bacteriorhodopsin (BR) can be kept soluble in its native state for months in the absence of detergent by amphipol (APol) A8-35, an amphiphilic polymer. After an actinic flash, A8-35-complexed BR undergoes a complete photocycle, with kinetics intermediate between that in detergent solution and that in its native membrane. BR/APol complexes form well defined, globular particles comprising a monomer of BR, a complete set of purple membrane lipids, and, in a peripheral distribution, ∼2 g APol/g BR, arranged in a compact layer. In the absence of free APol, BR/APol particles can autoassociate into small or large ordered fibrils.