Isomerization of retinal chromophore and conformational changes in membrane protein bacteriorhodopsin by solubilization with a mild non-ionic detergent, n-octyl-β-glucoside: an FT-Raman and FT-IR spectroscopic study

Sonoyama, Masashi; Hasegawa, Takeshi; Nakano, Takenori; Mitaku, Shigeki

doi:10.1016/j.vibspec.2003.12.008

Cited by 12 publications

(10 citation statements)

References 52 publications

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“…The native state of bR at pH 7 (before photobleaching) was characterized by an amide I band centered at 1660 cm )1 with an insignificant shoulder around 1630 cm )1 (Fig. 1a, trace (i)), as previously reported (16,20,(24)(25)(26). During photobleaching the amide I peak downshifted slightly to 1656 cm )1 and the shoulder at 1628 cm )1 became obvious ( Fig.…”

Section: Methodssupporting

confidence: 79%

“…Previous studies have shown that bR molecules undergo irreversible photobleaching in PM at high temperature (10,13,14), alkaline pH (11,16), and under solubilization by the mild nonionic detergent micelles, such as octylb-glucoside (12) and Triton X-100 (15). Under these conditions, similar structural changes were observed in bR molecules in the dark (monomeric-like state), including secondary structure, conformations around aromatic residues, retinal isomerization and disorganization of the 2D-crystalline array (13,(16)(17)(18)(19)(20). Taken together, the experimental findings of these studies strongly suggest that all forms of bR photobleaching in a PM may be attributed to a common mechanism.…”

Section: Introductionmentioning

confidence: 78%

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Structural Changes in Bacteriorhodopsin in Purple Membranes Induced by Irreversible Photobleaching with Heterogeneous and Homogeneous Stability

Yokoyama¹,

Sonoyama²,

Mitaku³

2010

Photochem & Photobiology

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Kinetic studies of irreversible photobleaching of bacteriorhodopsin (bR) in purple membrane (PM) at neutral pH have previously indicated the existence of two kinds of species which differ in their structural stability. bR was shown to have kinetically slow- and fast-decayed components with the faster one increasing with changes in intra- and intermolecular structures in darkness. However, our recent work reported that photobleaching kinetics above pH 10 were characterized by a single-decay component. In order to elucidate the factors responsible for the heterogeneous or homogeneous stability of photobleaching, we conducted investigations into the structural changes in bR in PM induced by photobleaching at pH 7 and 11 by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR spectra of bR photobleached at pH 7 and 11 showed that an increase in IR peak intensity at 1656 cm(-1) occurred simultaneously with decreases at 1666 cm(-1), indicating an alpha(II)-to-alpha(I) transition in transmembrane helices during photobleaching. The most significant change in IR spectra occurred at 1626 cm(-1) for samples photobleached at pH 7, and was attributed to structures formed between adjacent molecules. The origin of the heterogeneity of photobleaching is discussed on the basis of structural characteristics found in the bleached membranes.

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Section: Methodssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 78%

Structural Changes in Bacteriorhodopsin in Purple Membranes Induced by Irreversible Photobleaching with Heterogeneous and Homogeneous Stability

Yokoyama¹,

Sonoyama²,

Mitaku³

2010

Photochem & Photobiology

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“…In addition, larger surfactant shells are likely to exert a higher lateral pressure on the transmembrane helices than single surfactant layers, thereby favoring tertiary contacts between the helices that keep the chromophore in its functional conformation. Supporting this hypothesis is the observation that C 8 bG 1 -solubilized BR exhibits a much higher hydrogen/deuterium exchange of the peptide protons (65%) than in purple membrane (40%), indicating that the accessibility of the solvent to the protein interior has increased in the solubilized state (60). This situation was found to be linked to irreversible denaturation of the protein, which, in fact, occurs through destabilization of the helical assembly and consequent loss of the chromophore contacts.…”

Section: Discussionmentioning

confidence: 92%

Binding of Alkyl Polyglucoside Surfactants to Bacteriorhodopsin and its Relation to Protein Stability

Santonicola

Lenhoff

Kaler

2008

Biophysical Journal

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The binding of alkyl polyglucoside surfactants to the integral membrane protein bacteriorhodopsin (BR) and the formation of protein-surfactant complexes are investigated by sedimentation equilibrium via analytical ultracentrifugation and by small-angle neutron scattering (SANS). Contrast variation techniques in SANS enable measurement of the composition of the protein-surfactant complexes and determination of the thickness of the surfactant shell bound to the protein. The results indicate that alkyl polyglucosides can bind to BR as single surfactant layers or as a thicker shell. The thickness of the surfactant shell increases with increasing surfactant tail length, and it is generally unrelated to the aggregation number of the micelles even for a small and predominantly hydrophobic membrane protein such as BR. The aggregation numbers determined by sedimentation equilibrium methods match those measured by SANS, which also allows reconstruction of the shape of the protein-detergent complex. When the surfactant is present as a single layer, the BR loses activity, as measured by absorption spectroscopy, more quickly than it does when the surfactant forms a thicker shell.

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“…Lightinduced denaturation of bR molecules has been reported for bR solubilized with detergents, 3,8,9) reconstituted into phosphatidylcholine vesicles in the liquid-crystalline phase, 10,11) and in the purple membrane at high temperatures 7,12) and alkaline pH. 13) As pointed out in previous reports, 3,[11][12][13][14][15] light-induced denaturation of OTG-solubilized bR suggests destabilization of photointermediates, mainly due to weakening or disappearance of protein-protein interaction upon disassembly of trimeric bR molecules.…”

Section: )mentioning

confidence: 79%

Solubilization and Structural Stability of Bacteriorhodopsin with a Mild Nonionic Detergent,n-Octyl-β-thioglucoside

Asada

Sonoyama

2011

Bioscience, Biotechnology, and Biochemistry

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Isomerization of retinal chromophore and conformational changes in membrane protein bacteriorhodopsin by solubilization with a mild non-ionic detergent, n-octyl-β-glucoside: an FT-Raman and FT-IR spectroscopic study

Cited by 12 publications

References 52 publications

Structural Changes in Bacteriorhodopsin in Purple Membranes Induced by Irreversible Photobleaching with Heterogeneous and Homogeneous Stability

Structural Changes in Bacteriorhodopsin in Purple Membranes Induced by Irreversible Photobleaching with Heterogeneous and Homogeneous Stability

Binding of Alkyl Polyglucoside Surfactants to Bacteriorhodopsin and its Relation to Protein Stability

Solubilization and Structural Stability of Bacteriorhodopsin with a Mild Nonionic Detergent,n-Octyl-β-thioglucoside

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