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Chang CH, Jonas R, Melchiore S, Govindjee R, Ebrey TG. Mechanism and role of divalent cation binding of bacteriorhodopsin. Biophys J 2010; 49:731-9. [PMID: 19431671 DOI: 10.1016/s0006-3495(86)83699-2] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Several observations have already suggested that the carboxyl groups are involved in the association of divalent cations with bacteriorhodopsin (Chang et al., 1985). Here we show that at least part of the protons released from deionized purple membrane (;blue membrane') samples when salt is added are from carboxyl groups. We find that the apparent pK of magnesium binding to purple membrane in the presence of 0.5 mM buffer is 5.85. We suggest this is the pK of the carboxyl groups shifted from their usual pK because of the proton concentrating effect of the large negative surface potential of the purple membrane. Divalent cations may interact with negatively charged sites on the surface of purple membrane through the surface potential and/or through binding either by individual ligands or by conformation-dependent chelation. We find that divalent cations can be released from purple membrane by raising the temperature. Moreover, purple membrane binds only about half as many divalent cations after bleaching. Neither of these operations is expected to decrease the surface potential and thus these experiments suggest that some specific conformation in purple membrane is essential for the binding of a substantial fraction of the divalent cations. Divalent cations in purple membrane can be replaced by monovalent, (Na(+) and K(+)), or trivalent, (La(+++)) cations. Flash photolysis measurements show that the amplitude of the photointermediate, O, is affected by the replacement of the divalent cations by other ions, especially by La(+++). The kinetics of the M photointermediate and light-induced H(+) uptake are not affected by Na(+) and K(+), but they are drastically lengthened by La(+++) substitution, especially at alkaline pHs. We suggest that the surface charge density and thus the surface potential is controlled by divalent cation binding. Removal of the cations (to make deionized blue membrane) or replacement of them (e.g. La(+++)-purple membrane) changes the surface potential and hence the proton concentration near the membrane surface. An increase in local proton concentration could cause the protonation of critical carboxyl groups, for example the counter-ion to the protonated Schiff's base, causing the red shift associated with the formation of both deionized and acid blue membrane. Similar explanations based on regulation of the surface proton concentration can explain many other effects associated with the association of different cations with bacteriorhodopsin.
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Neebe M, Rhinow D, Schromczyk N, Hampp NA. Thermochromism of Bacteriorhodopsin and Its pH Dependence. J Phys Chem B 2008; 112:6946-51. [DOI: 10.1021/jp7111389] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Martin Neebe
- Department of Chemistry, University of Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Daniel Rhinow
- Department of Chemistry, University of Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Nina Schromczyk
- Department of Chemistry, University of Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Norbert A. Hampp
- Department of Chemistry, University of Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
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Jin Y, Friedman N, Cahen D, Sheves M. Chemically induced enhancement of the opto-electronic response of Halobacterium purple membrane monolayer. Chem Commun (Camb) 2006:1310-2. [PMID: 16538257 DOI: 10.1039/b518268a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acetylation of purple membranes (PM) significantly enhances the surface photovoltage that they exhibit, if adsorbed as a monolayer on a solid surface; we suggest that this increase is due to the improved orientation of the PM on the surface.
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Affiliation(s)
- Yongdong Jin
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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Maeda A, Ogura T, Kitagawa T. Resonance Raman study on proton-dissociated state of bacteriorhodopsin: stabilization of L-like intermediate having the all-trans chromophore. Biochemistry 2002. [DOI: 10.1021/bi00358a010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wang G, Hu KS. Effects of pH and acetylation on Hg(2+)-induced purple to blue transition in bacteriorhodopsin. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2001; 60:97-101. [PMID: 11470564 DOI: 10.1016/s1011-1344(01)00126-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Effects of Hg(2+) ions on the absorption spectrum of bacteriorhodopsin have been measured at different pH values and after acetylation. UV-difference spectroscopy and CD spectra show that Hg(2+)-induced color change is essentially similar to that caused by removal of cations or acidification. The ability of Hg(2+)-induced purple-to-blue transition is pH-dependent and exhibits a maximum at pH 5.5. Acetylation influences the absorption in the same way as Hg(2+) ions and accelerates Hg(2+)-induced purple to blue transition. All these results strongly suggest that the Hg(2+) effect is not a specific binding but just a replacement of intrinsic cations on the membrane surface, where they form a double layer. The composition of the double layer determines the surface pH on the membrane, which affects the color of the bacteriorhodopsin.
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Affiliation(s)
- G Wang
- Institute of Biophysics, Academia Sinica, 15 Datun Road, 100101, Beijing, China
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Gergely C, Zimányi L, Váró G. Bacteriorhodopsin Intermediate Spectra Determined over a Wide pH Range. J Phys Chem B 1997. [DOI: 10.1021/jp971381e] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Csilla Gergely
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - László Zimányi
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - György Váró
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
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7
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Rivière ME, Arrio B, Pansu R, Faure J. Influence of the surface potential on the purple membrane structure and activity. Arch Biochem Biophys 1991; 284:1-8. [PMID: 1989488 DOI: 10.1016/0003-9861(91)90253-f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The role of the divalent cations in the purple membrane is generally understood as the release mechanism of the blue form appearance. The reconstitution by cation addition leads to the recovery of the initial spectral properties. Numerous data are available in the literature on this matter but they are scattered, so that synthetic understanding is not easy. The role of divalent cations was studied through spectrophotometric titrations and electrophoretic mobility measurements, i.e., zeta potential valuations. Thus, correlations between the bacteriorhodopsin (bR) state and the whole membrane in equilibrium with a definite medium could be made. Deionization was not a fully reversible process. The absence of cations affect neither the rate of the M412 formation nor its lifetime but the yield of M412/bR was 50% lower. The number of protons involved in the blue to purple transition of both membranes was different and the reconstitution did not erase this difference. It was observed that the number of protons dissociated upon cation addition corresponded approximately to the number of positive charges removed by deionization. Electrophoretic mobility titrations showed large differences between the membranes, illustrating the influence of the surface charge density on the pK of the transition. Taking advantage of the reversible light adaptation process, the reciprocal influence of the charge density of the membrane surface and the retinal state in bR was shown. Specificity of the divalent cations was questioned by a direct substitution of them by imidazol, which left the membrane intact. The partial reversibility of the deionization, the decrease of the M412 yield, the differences in the titratable protons, and the nonstrict specificity toward divalent cations suggested that another unknown factor could be removed from the membrane.
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Affiliation(s)
- M E Rivière
- C.N.R.S. URA 1116, Bioénergétique Membranaire, Bât. 433, Université de Paris-Sud, Orsay, France
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Formation of blue membrane of bacteriorhodopsin by addition of tetrakis(4-fluorophenyl)boron, an hydrophobic anion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1987. [DOI: 10.1016/0005-2736(87)90366-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Szundi I, Stoeckenius W. Effect of lipid surface charges on the purple-to-blue transition of bacteriorhodopsin. Proc Natl Acad Sci U S A 1987; 84:3681-4. [PMID: 3473476 PMCID: PMC304939 DOI: 10.1073/pnas.84.11.3681] [Citation(s) in RCA: 101] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Purple membrane (lambda max = 568 nm) can be converted to blue membrane (lambda max = 605 nm) by either acid titration or deionization. Partially delipidated purple membrane, containing only 25% of the initial lipid phosphorus, could be converted to a blue form by acid titration but not by deionization. This reversible transition of delipidated membrane did not require the presence of other cations, and the pK of the color change that in native membrane under similar conditions is between 3.0 and 4.0 was shifted to 1.4. We conclude that the purple-to-blue transition is controlled by proton concentration only and that, in native membranes, the cations act only by raising the low surface pH generated by the acidic groups of the lipids. The observation that extraction of lipids from deionized native membrane converts its color from blue to purple further confirms this conclusion. The two states of the membrane probably reflect two preferred conformations of bacteriorhodopsin, which are controlled by protonation changes at the surface of the membrane and differ slightly in the spatial distribution of charges around the chromophore.
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Abercrombie DM, Khorana HG. Regeneration of native bacteriorhodopsin structure following acetylation of epsilon-amino groups of Lys-30, -40, and -41. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)89186-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Hiraki K, Hamanaka T, Mitsui T, Kito Y. The absorbance spectrum of the brown holo-membrane and the comparison of pI values of bacteriorhodopsin solubilized from purple membrane and from brown holo-membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1984. [DOI: 10.1016/0005-2736(84)90425-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Maeda A, Asato AE, Liu RS, Yoshizawa T. Interaction of aromatic retinal analogues with apopurple membranes of Halobacterium halobium. Biochemistry 1984; 23:2507-13. [PMID: 6477881 DOI: 10.1021/bi00306a029] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Absorption spectral properties of aromatic analogues of retinal with apopurple membrane of Halobacterium halobium were studied. The spectra of the all-trans forms were composed of two or more absorption bands. During incubation at 20 degrees C, an absorption band above 500 nm increased in intensity gradually at the expense of an absorption band in the shorter wavelength region with no isomerization of the chromophore. The longer wavelength species was shown to be the protonated form of the shorter wavelength species by changing the pH of the medium. Upon irradiation with blue light, the bandwidth of the spectrum became smaller with isomerization of the chromophore to its 13-cis form. Irreversible binding of protons on the membrane occurred during this process. The rate of the increase in the longer wavelength absorption band was especially low in the reaction with the all-trans form of retinal analogues having a bulky substituent at the para or meta positions of the phenyl ring. In contrast, the 13-cis isomer of aromatic retinal analogues gave a single absorption peak. The extent of the spectral shift upon binding to apopurple membranes was compared over a series of aromatic retinals, and the results were explained in terms of steric interactions of the chromophore with the protein.
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Padrós E, Duñach M, Sabés M. Induction of the blue form of bacteriorhodopsin by low concentrations of sodium dodecyl sulfate. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 769:1-7. [PMID: 6691969 DOI: 10.1016/0005-2736(84)90002-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effects produced on bacteriorhodopsin by low concentrations of several detergents have been studied by absorption and fourth-derivative spectrophotometry. Sodium dodecyl sulfate induces the appearance of the blue form of bacteriorhodopsin (lambda max = 600 nm) at pH values up to 7.0 in a reversible manner. The apparent pK of the purple-to-blue transition raised with increasing concentration of SDS. Of the other detergents tested, only sodium dodecyl-N-sarcosinate showed a slight red-shift of the absorption band to 580 nm, whereas sodium taurocholate, Triton X-100 and cetyltrimethylammonium bromide did not favour the appearance of the blue form. The effect of SDS was found to be consistent with a localized conformational change that moves away the counter-ion of the protonated Schiff base.
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Lanyi JK. Chapter 11 Bacteriorhodopsin and related light-energy converters. NEW COMPREHENSIVE BIOCHEMISTRY 1984. [DOI: 10.1016/s0167-7306(08)60321-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Dencher NA. THE FIVE RETINAL-PROTEIN PIGMENTS OF HALOBACTERIA: BACTERIORHODOPSIN, HALORHODOPSIN, P 565, P 370, AND SLOW-CYCLING RHODOPSIN. Photochem Photobiol 1983. [DOI: 10.1111/j.1751-1097.1983.tb03611.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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