Temperature-dependent aggregation of bacteriorhodopsin in dipalmitoyl- and dimyristoylphosphatidylcholine vesicles

Cherry, Richard J.; Müller, Ulrike; Henderson, Richard A.; Heyn, Maarten P.

doi:10.1016/s0022-2836(78)80010-2

Cited by 159 publications

(133 citation statements)

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“…A similar signal is detectable in BR, reconstituted into liposomes, and analyzed below the phase transition temperature (T c ) of the phospholipids used (15,19). However, above T c , the excitonic effects disappear, and only at high protein-to-lipid ratios (Ͼ1:10 w/w) is a considerable amount of exciton coupling observed (19). The disappearance of the exciton component in the CD spectrum has been interpreted as dissociation of the aggregate, yielding a monomeric dispersion of BR in the plane of the membrane (15).…”

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confidence: 83%

“…In the CD spectrum, the purple membrane exhibits a characteristic excitonic signal caused by interactions between the protein chromophores in the closely packed hexagonal lattice (18). A similar signal is detectable in BR, reconstituted into liposomes, and analyzed below the phase transition temperature (T c ) of the phospholipids used (15,19). However, above T c , the excitonic effects disappear, and only at high protein-to-lipid ratios (Ͼ1:10 w/w) is a considerable amount of exciton coupling observed (19).…”

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confidence: 90%

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Spatial Organization of Bacteriorhodopsin in Model Membranes

Kahya

Wiersma

Poolman

et al. 2002

Journal of Biological Chemistry

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Bacteriorhodopsin is a proton-transporting membrane protein in Halophilic archaea, and it is considered a prototype of membrane transporters and a model for G-protein-coupled receptors. Oligomerization of the protein has been reported, but it is unknown whether this feature is correlated with, for instance, light activation. Here, we have addressed this issue by reconstituting bacteriorhodopsin into giant unilamellar vesicles. The dynamics of the fully active protein was investigated using fluorescence correlation spectroscopy and freeze fracture electron microscopy. At low protein-tolipid ratios (<1:10 w/w), a decrease in mobility was observed upon protein photoactivation. This process occurred on a second time scale and was fully reversible, i.e. when the dark-adapted state was reestablished the lateral diffusion rate of the protein was returned to that prior to activation. A similar decrease in lateral mobility as observed upon photoactivation was obtained when bacteriorhodopsin was reconstituted at high protein-tolipid ratios (>1:10 w/w). We interpret the shifts in mobility during light adaptation as being caused by transient photoinduced oligomerization of bacteriorhodopsin. These observations are fully supported by freeze-fracture electron microscopy, and the size of the clusters during photoactivation was estimated to consist of two or three trimers.

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confidence: 83%

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confidence: 90%

Spatial Organization of Bacteriorhodopsin in Model Membranes

Kahya

Wiersma

Poolman

et al. 2002

Journal of Biological Chemistry

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“…In bacteriorhodopsin containing phosphatidylcholine vesicles, reversible aggregation of bacteriorhodopsin can be induced by lowering the temperature [S] . Whereas the hexagonally aggregated state of the protein is characterized by an exciton CD spectrum, the monomeric state is characterized by a positive CD band centered at the absorption maximum [5]. A similar 'monomer' or intrinsic CD band is also observed with monomeric rhodopsin [6].…”

Section: Introductionmentioning

confidence: 90%

“…The low critical micelle concentration (0.24 mM) is a disadvantage in this procedure. During dialysis, reassembly occurs and large hexagonal crystalline domains are formed again [5]. In the course of this reassembly process the absorption maximum in the light-adapted state shifts back to 568 nm, the exciton CD bands reappear and the CD at 3 I8 nm resumes its original value.…”

Section: Solubilization In Triton X-l 00mentioning

confidence: 99%

Formation and properties of bacteriorhodopsin monomers in the non‐ionic detergents octyl‐β‐D‐glucoside and triton X‐100

Dencher¹,

Heyn²

1978

FEBS Letters

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184

124

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“…Several reports on the lateral (3-7) and rotational diffusion (8,9) of components in the plane of the membrane in model membrane systems have appeared. In model membranes, as opposed to biomembranes, it is possible in principle to examine simple membrane compositions-for example, one protein and one lipid membrane-and subsequently to increase the complexity of the system at will.…”

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confidence: 99%

Lateral mobility of an amphipathic apolipoprotein, ApoC-III, bound to phosphatidylcholine bilayers with and without cholesterol

Vaz

Jacobson

et al. 1979

Proc. Natl. Acad. Sci. U.S.A.

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The technique of fluorescence recovery after photobleaching was used to investigate the lateral mobility of a fluorescein-labeled amphipathic apolipoprotein, ApoC-II, bound to multibilayers prepared from dipalmitoyl phosphatidylcholine, egg phosphatidylcholine, and a 1:1 (molar ratio) mixture of egg phosphatidylcholine and cholesterol. In dipalmitoyl phosphatidylcholine bilayers the lateral diffusion coefficient (D) for the protein is about 2 X 10-9 cm2 sec1 at 200C and about 9 X 10-s cm2 sec1 at 450C. Plots The mobility of membrane components has drawn considerable attention in the recent literature (1, 2). Several reports on the lateral (3-7) and rotational diffusion (8, 9) of components in the plane of the membrane in model membrane systems have appeared. In model membranes, as opposed to biomembranes, it is possible in principle to examine simple membrane compositions-for example, one protein and one lipid membrane-and subsequently to increase the complexity of the system at will. In this manner, it is possible to learn about the influence of a given membrane component on the diffusion of other components in the membrane and also, by comparison to natural membrane diffusion results, to learn about the role that nonmembrane components in the cell play in the regulation of membrane component mobility.In the present communication we report the use of the technique of fluorescence recovery after photobleaching (FRAP) to study the lateral diffusion of an amphipathic apolipoprotein, ApoC-III, in bilayer membranes formed from dipalmitoyl phosphatidylcholine (Pam2PtdCho), egg-yolk phosphatidyl-choline (E-PtdCho), and an equimolar mixture of E-PtdCho and cholesterol (Chol). The results have been communicated in a preliminary form (10). FRAP has been used so far to study a wide range of natural membrane (11-21) and model membrane systems (3-7). It offers a convenient method for studying lateral diffusion and is particularly attractive from the points of view of experimental and theoretical simplicity (19,22).ApoC-III is an amphipathic peptide having a molecular weight of about 9000 and a known amino acid sequence (23,24). Its interaction with lipid membranes has been extensively studied (24). It interacts with E-PtdCho (25) MATERIALS AND METHODS ApoC-III was isolated according to the procedure of Brown et al. (28) and was labeled with fluorescein by reaction of the protein (1 mg/ml) in 0.1 M sodium borate buffer at pH 9.0 with a 100-fold molar excess of fluorescein isothiocyanate (Baltimore Biological Laboratory Division, Becton-Dickinson) for 1 hr at 250C. After reaction, the labeled protein (dye/protein ratio = 2) was separated from unreacted dye by filtration through a column of Sephadex G-25 using Dulbecco's Ca2+-and Mg2+-free phosphate-buffered saline.The phospholipids used in this study were isolated or synthesized by Tom Isac in the laboratory of D. Papahadjopoulos. Pam2PtdCho was synthesized as described by Robles and Van Den Berg (29) and E-PtdCho was isolated from egg yolks as described by Papah...

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Temperature-dependent aggregation of bacteriorhodopsin in dipalmitoyl- and dimyristoylphosphatidylcholine vesicles

Cited by 159 publications

References 50 publications

Spatial Organization of Bacteriorhodopsin in Model Membranes

Spatial Organization of Bacteriorhodopsin in Model Membranes

Formation and properties of bacteriorhodopsin monomers in the non‐ionic detergents octyl‐β‐D‐glucoside and triton X‐100

Lateral mobility of an amphipathic apolipoprotein, ApoC-III, bound to phosphatidylcholine bilayers with and without cholesterol

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