The role of retinal in the long-range protein-lipid interactions in bacteriorhodopsin-phosphatidylcholine vesicles
1Department of Physics and Biophysics, University of Warmia and Mazury in Olsztyn, Poland. kris@moskit.uwm.edu.pl
Abstract:
The effects of bacteriorhodopsin analogues and the analogues of a bacteriorhodopsin mutant (D96N) on the lateral organization of lipids have been investigated with lipid species with a variety of acyl chain lengths. The analogues, obtained by regeneration of bacterioopsin or mutant opsin with 14-, 12-, 10-, or 8-fluororetinal, were reconstituted with 1,2-didodecanoyl-sn-glycero-3-phosphocholine, 1,2-ditetradecanoyl-sn-glycero-3-phosphocholine, 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine, and 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine. The phase behavior of the protein-lipid systems was investigated at different temperatures and different protein/lipid molar ratios by analyzing the fluorescence and phase properties of the 1-acyl-2-[8-(2-anthroyl)octanol]-sn-glycero-3-phosphocholine probe. The (8,10,12)-bacteriorhodopsins had a similar effect on the lipid phase transition to that induced by native bacteriorhodopsin: a rigidifying effect on the three shorter lipid species and a fluidifying effect on the longest-chain lipids used. The substitution of retinal with 14-fluororetinal resulted in much stronger effects of the protein on the lipids: a more pronounced up-shift of the lipid phase transition temperature, a rigidifying effect on all the lipids used, and an elongation of the distance over which the hydrophobic thickness of the lipid bilayer was perturbed by the protein. Evidence was provided that retinal contributed to the long-range protein-lipid interactions in bacteriorhodopsin-phosphatidylcholine vesicles. The extent of this contribution was dependent on the retinal structure in close vicinity to the Shiff base and on the compactness of the protein structure.
Related Concept Videos
Channel Rhodopsins
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Asymmetric Lipid Bilayer
Assembly of the Lipid Bilayer in the ER
A large chunk of any biological membrane is composed of phospholipids. These lipids have a heterogeneous distribution across different subcellular organelles and even between...
Photoreceptors and Visual Pathways
Rab Proteins
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Phosphoinositides and PIPs
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...


