1
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Asido M, Boumrifak C, Weissbecker J, Bamberg E, Wachtveitl J. Vibrational Study of the Inward Proton Pump Xenorhodopsin NsXeR: Switch Order Determines Vectoriality. J Mol Biol 2024; 436:168447. [PMID: 38244766 DOI: 10.1016/j.jmb.2024.168447] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 01/12/2024] [Accepted: 01/12/2024] [Indexed: 01/22/2024]
Abstract
Common proton pumps, e.g. HsBR and PR, transport protons out of the cell. Xenorhodopsins (XeR) were the first discovered microbial rhodopsins which come as natural inward proton pumps. In this work we combine steady-state (cryo-)FTIR and Raman spectroscopy with time-resolved IR and UV/Vis measurements to roadmap the inward proton transport of NsXeR and pinpoint the most important mechanistic features. Through the assignment of characteristic bands of the protein backbone, the retinal chromophore, the retinal Schiff base and D220, we could follow the switching processes for proton accessibility in accordance with the isomerization / switch / transfer model. The corresponding transient IR signatures suggest that the initial assignment of D220 as the proton acceptor needs to be questioned due to the temporal mismatch of the Schiff base and D220 protonation steps. The switching events in the K-L and MCP-MEC transitions are finely tuned by changes of the protein backbone and rearrangements of the Schiff base. This finely tuned mechanism is disrupted at cryogenic temperatures, being reflected in the replacement of the previously reported long-lived intermediate GS* by an actual redshifted (O-like) intermediate.
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Affiliation(s)
- Marvin Asido
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany
| | - Chokri Boumrifak
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany
| | - Juliane Weissbecker
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Ernst Bamberg
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
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2
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Hontani Y, Ganapathy S, Frehan S, Kloz M, de Grip WJ, Kennis JTM. Strong pH-Dependent Near-Infrared Fluorescence in a Microbial Rhodopsin Reconstituted with a Red-Shifting Retinal Analogue. J Phys Chem Lett 2018; 9:6469-6474. [PMID: 30376338 PMCID: PMC6240888 DOI: 10.1021/acs.jpclett.8b02780] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 10/30/2018] [Indexed: 06/08/2023]
Abstract
Near-infrared (NIR)-driven rhodopsins are of great interest in optogenetics and other optobiotechnological developments such as artificial photosynthesis and deep-tissue voltage imaging. Here we report that the proton pump proteorhodopsin (PR) containing a NIR-active retinal analogue (PR:MMAR) exhibits intense NIR fluorescence at a quantum yield of 3.3%. This is 130 times higher than native PR ( Lenz , M. O. ; Biophys J. 2006 , 91 , 255 - 262 ) and 3-8 times higher than the QuasAr and PROPS voltage sensors ( Kralj , J. ; Science 2011 , 333 , 345 - 348 ; Hochbaum , D. R. ; Nat. Methods 2014 , 11 , 825 - 833 ). The NIR fluorescence strongly depends on the pH in the range of 6-8.5, suggesting potential application of MMAR-binding proteins as ultrasensitive NIR-driven pH and/or voltage sensors. Femtosecond transient absorption spectroscopy showed that upon near-IR excitation, PR:MMAR features an unusually long fluorescence lifetime of 310 ps and the absence of isomerized photoproducts, consistent with the high fluorescence quantum yield. Stimulated Raman analysis indicates that the NIR-absorbing species develops upon protonation of a conserved aspartate, which promotes charge delocalization and bond length leveling due to an additional methylamino group in MMAR, in essence providing a secondary protonated Schiff base. This results in much smaller bond length alteration along the conjugated backbone, thereby conferring significant single-bond character to the C13═C14 bond and structural deformation of the chromophore, which interferes with photoinduced isomerization and extends the lifetime for fluorescence. Hence, our studies allow for a molecular understanding of the relation between absorption/emission wavelength, isomerization, and fluorescence in PR:MMAR. As acidification enhances the resonance state, this explains the strong pH dependence of the NIR emission.
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Affiliation(s)
- Yusaku Hontani
- Department
of Physics and Astronomy, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands
| | - Srividya Ganapathy
- Department
of Biophysical Organic Chemistry, Leiden Institute of
Chemistry, Gorlaeus Laboratories, Leiden University, Leiden 2300 RA, The Netherlands
| | - Sean Frehan
- Department
of Physics and Astronomy, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands
| | - Miroslav Kloz
- Department
of Physics and Astronomy, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands
- ELI-Beamlines,
Institute of Physics, Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - Willem J. de Grip
- Department
of Biophysical Organic Chemistry, Leiden Institute of
Chemistry, Gorlaeus Laboratories, Leiden University, Leiden 2300 RA, The Netherlands
- Department
of Biochemistry, Radboud University Medical
Center, Nijmegen 6500 HB, The Netherlands
| | - John T. M. Kennis
- Department
of Physics and Astronomy, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands
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3
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Jawurek M, Dröden J, Peter B, Glaubitz C, Hauser K. Lipid-induced dynamics of photoreceptors monitored by time-resolved step-scan FTIR spectroscopy. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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4
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Köhler T, Weber I, Glaubitz C, Wachtveitl J. Proteorhodopsin Photocycle Kinetics Between pH 5 and pH 9. Photochem Photobiol 2017; 93:762-771. [DOI: 10.1111/php.12753] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/25/2017] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas Köhler
- Institute of Physical and Theoretical Chemistry; Goethe Universität Frankfurt am Main; Frankfurt Germany
| | - Ingrid Weber
- Institut für Biophysikalische Chemie; Goethe Universität Frankfurt am Main; Frankfurt Germany
| | - Clemens Glaubitz
- Institut für Biophysikalische Chemie; Goethe Universität Frankfurt am Main; Frankfurt Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry; Goethe Universität Frankfurt am Main; Frankfurt Germany
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5
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Eckert CE, Kaur J, Glaubitz C, Wachtveitl J. Ultrafast Photoinduced Deactivation Dynamics of Proteorhodopsin. J Phys Chem Lett 2017; 8:512-517. [PMID: 28072545 DOI: 10.1021/acs.jpclett.6b02975] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report femtosecond time-resolved absorption change measurements of the photoinduced deactivation dynamics of a microbial rhodopsin in the ultraviolet-visible and mid-infrared range. The blue light quenching process is recorded in green proteorhodopsin's (GPR) primary proton donor mutant E108Q from the deprotonated 13-cis photointermediate. The return of GPR to the dark state occurs in two steps, starting with the photoinduced 13-cis to all-trans reisomerization of the retinal. The subsequent Schiff base reprotonation via the primary proton acceptor (D97) occurs on a nanosecond time scale. This step is two orders of magnitude faster than that in bacteriorhodopsin, potentially because of the very high pKA of the GPR primary proton acceptor.
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Affiliation(s)
- C Elias Eckert
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main , Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany
| | - Jagdeep Kaur
- Institute of Biophysical Chemistry, Goethe-University Frankfurt am Main , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
| | - Clemens Glaubitz
- Institute of Biophysical Chemistry, Goethe-University Frankfurt am Main , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt am Main , Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany
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6
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Modulation of spectral properties and pump activity of proteorhodopsins by retinal analogues. Biochem J 2015; 467:333-43. [DOI: 10.1042/bj20141210] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Microbial proteorhodopsins are light-driven proton pumps, using the vitamin A derivative retinal as chromophore. We show that retinal analogues can shift their absorbance band with preservation of functionality. This may provide attractive opportunities in biotechnology, optogenetics and as potential sensors.
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7
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Huang YH, Chen JD, Hsu KH, Chu LK, Lee YP. Transient Infrared Absorption Spectra of Reaction Intermediates Detected with a Step-scan Fourier-transform Infrared Spectrometer. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.201300415] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Bamann C, Bamberg E, Wachtveitl J, Glaubitz C. Proteorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:614-25. [PMID: 24060527 DOI: 10.1016/j.bbabio.2013.09.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/11/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
Abstract
Proteorhodopsins are the most abundant retinal based photoreceptors and their phototrophic function might be relevant in marine ecosystems. Here, we describe their remarkable molecular properties with a special focus on the green absorbing variant. Its distinct features include a high pKa value of the primary proton acceptor stabilized through an interaction with a conserved histidine, a long-range interaction between the cytoplasmic EF loop and the chromophore entailing a particular mode of color tuning and a variable proton pumping vectoriality with complex voltage-dependence. The proteorhodopsin family represents a profound example for structure-function relationships. Especially the development of a biophysical understanding of green proteorhodopsin is an excellent example for the unique opportunities offered by a combined approach of advanced spectroscopic and electrophysiological methods. This article is part of a Special Issue entitled: Retinal Proteins-You can teach an old dog new tricks.
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Affiliation(s)
- Christian Bamann
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany.
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany
| | - Josef Wachtveitl
- Johann Wolfgang Goethe University, Institute for Physical and Theoretical Chemistry, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany
| | - Clemens Glaubitz
- Johann Wolfgang Goethe University, Institute for Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
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9
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Brown LS. Eubacterial rhodopsins - unique photosensors and diverse ion pumps. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:553-61. [PMID: 23748216 DOI: 10.1016/j.bbabio.2013.05.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 05/27/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022]
Abstract
Since the discovery of proteorhodopsins, the ubiquitous marine light-driven proton pumps of eubacteria, a large number of other eubacterial rhodopsins with diverse structures and functions have been characterized. Here, we review the body of knowledge accumulated on the four major groups of eubacterial rhodopsins, with the focus on their biophysical characterization. We discuss advances and controversies on the unique eubacterial sensory rhodopsins (as represented by Anabaena sensory rhodopsin), proton-pumping proteorhodopsins and xanthorhodopsins, as well as novel non-proton ion pumps. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- Leonid S Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Ontario N1G 2W1, Canada.
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10
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Aspartate-histidine interaction in the retinal schiff base counterion of the light-driven proton pump of Exiguobacterium sibiricum. Biochemistry 2012; 51:5748-62. [PMID: 22738070 DOI: 10.1021/bi300409m] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One of the distinctive features of eubacterial retinal-based proton pumps, proteorhodopsins, xanthorhodopsin, and others, is hydrogen bonding of the key aspartate residue, the counterion to the retinal Schiff base, to a histidine. We describe properties of the recently found eubacterium proton pump from Exiguobacterium sibiricum (named ESR) expressed in Escherichia coli, especially features that depend on Asp-His interaction, the protonation state of the key aspartate, Asp85, and its ability to accept a proton from the Schiff base during the photocycle. Proton pumping by liposomes and E. coli cells containing ESR occurs in a broad pH range above pH 4.5. Large light-induced pH changes indicate that ESR is a potent proton pump. Replacement of His57 with methionine or asparagine strongly affects the pH-dependent properties of ESR. In the H57M mutant, a dramatic decrease in the quantum yield of chromophore fluorescence emission and a 45 nm blue shift of the absorption maximum with an increase in the pH from 5 to 8 indicate deprotonation of the counterion with a pK(a) of 6.3, which is also the pK(a) at which the M intermediate is observed in the photocycle of the protein solubilized in detergent [dodecyl maltoside (DDM)]. This is in contrast with the case for the wild-type protein, for which the same experiments show that the major fraction of Asp85 is deprotonated at pH >3 and that it protonates only at low pH, with a pK(a) of 2.3. The M intermediate in the wild-type photocycle accumulates only at high pH, with an apparent pK(a) of 9, via deprotonation of a residue interacting with Asp85, presumably His57. In liposomes reconstituted with ESR, the pK(a) values for M formation and spectral shifts are 2-3 pH units lower than in DDM. The distinctively different pH dependencies of the protonation of Asp85 and the accumulation of the M intermediate in the wild-type protein versus the H57M mutant indicate that there is strong Asp-His interaction, which substantially lowers the pK(a) of Asp85 by stabilizing its deprotonated state.
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11
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Herz J, Verhoefen MK, Weber I, Bamann C, Glaubitz C, Wachtveitl J. Critical role of Asp227 in the photocycle of proteorhodopsin. Biochemistry 2012; 51:5589-600. [PMID: 22738119 DOI: 10.1021/bi3003764] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The photocycle of the proton acceptor complex mutant D227N of the bacterial retinal protein proteorhodopsin is investigated employing steady state pH-titration experiments in the UV-visible range as well as femtosecond-pump-probe spectroscopy and flash photolysis in the visible spectral range. The evaluation of the pH-dependent spectra showed that the neutralization of the charge at position 227 has a remarkable influence on the ground state properties of the protein. Both the pK(a) values of the primary proton acceptor and of the Schiff base are considerably decreased. Femtosecond-time-resolved measurements demonstrate that the general S(1) deactivation pathway; that is, the K-state formation is preserved in the D227N mutant. However, the pH-dependence of the reaction rate is lost by the substitution of Asp227 with an asparagine. Also no significant kinetic differences are observed upon deuteration. This is explained by the lack of a strongly hydrogen-bonded water in the vicinity of Asp97, Asp227, and the Schiff base or a change in the hydrogen bonding of it (Ikeda et al. (2007) Biochemistry 46, 5365-5373). The flash photolysis measurements prove a considerably elongated photocycle with pronounced pH-dependence. Interestingly, at pH 9 the M-state is visible until the end of the reaction cycle, leading to the conclusion that the mutation does not only lower the pK(a) of the Schiff base in the unphotolyzed ground state but also prevents an efficient reprotonation reaction.
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Affiliation(s)
- Julia Herz
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany
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12
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Low temperature FTIR spectroscopy provides new insights in the pH-dependent proton pathway of proteorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1583-90. [DOI: 10.1016/j.bbabio.2011.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 08/25/2011] [Accepted: 09/05/2011] [Indexed: 11/15/2022]
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13
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Ranaghan MJ, Schwall CT, Alder NN, Birge RR. Green proteorhodopsin reconstituted into nanoscale phospholipid bilayers (nanodiscs) as photoactive monomers. J Am Chem Soc 2011; 133:18318-27. [PMID: 21951206 PMCID: PMC3218432 DOI: 10.1021/ja2070957] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Over 4000 putative proteorhodopsins (PRs) have been identified throughout the oceans and seas of the Earth. The first of these eubacterial rhodopsins was discovered in 2000 and has expanded the family of microbial proton pumps to all three domains of life. With photophysical properties similar to those of bacteriorhodopsin, an archaeal proton pump, PRs are also generating interest for their potential use in various photonic applications. We perform here the first reconstitution of the minimal photoactive PR structure into nanoscale phospholipid bilayers (nanodiscs) to better understand how protein-protein and protein-lipid interactions influence the photophysical properties of PR. Spectral (steady-state and time-resolved UV-visible spectroscopy) and physical (size-exclusion chromatography and electron microscopy) characterization of these complexes confirms the preparation of a photoactive PR monomer within nanodiscs. Specifically, when embedded within a nanodisc, monomeric PR exhibits a titratable pK(a) (6.5-7.1) and photocycle lifetime (∼100-200 ms) that are comparable to the detergent-solubilized protein. These ndPRs also produce a photoactive blue-shifted absorbance, centered at 377 or 416 nm, that indicates that protein-protein interactions from a PR oligomer are required for a fast photocycle. Moreover, we demonstrate how these model membrane systems allow modulation of the PR photocycle by variation of the discoidal diameter (i.e., 10 or 12 nm), bilayer thickness (i.e., 23 or 26.5 Å), and degree of saturation of the lipid acyl chain. Nanodiscs also offer a highly stable environment of relevance to potential device applications.
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Affiliation(s)
- Matthew J. Ranaghan
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269 (USA)
| | - Christine T. Schwall
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269 (USA)
| | - Nathan N. Alder
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269 (USA)
| | - Robert R. Birge
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269 (USA)
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269 (USA)
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14
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Malmerberg E, Omran Z, Hub JS, Li X, Katona G, Westenhoff S, Johansson LC, Andersson M, Cammarata M, Wulff M, van der Spoel D, Davidsson J, Specht A, Neutze R. Time-resolved WAXS reveals accelerated conformational changes in iodoretinal-substituted proteorhodopsin. Biophys J 2011; 101:1345-53. [PMID: 21943415 DOI: 10.1016/j.bpj.2011.07.050] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/15/2011] [Accepted: 07/15/2011] [Indexed: 12/20/2022] Open
Abstract
Time-resolved wide-angle x-ray scattering (TR-WAXS) is an emerging biophysical method which probes protein conformational changes with time. Here we present a comparative TR-WAXS study of native green-absorbing proteorhodopsin (pR) from SAR86 and a halogenated derivative for which the retinal chromophore has been replaced with 13-desmethyl-13-iodoretinal (13-I-pR). Transient absorption spectroscopy differences show that the 13-I-pR photocycle is both accelerated and displays more complex kinetics than native pR. TR-WAXS difference data also reveal that protein structural changes rise and decay an order-of-magnitude more rapidly for 13-I-pR than native pR. Despite these differences, the amplitude and nature of the observed helical motions are not significantly affected by the substitution of the retinal's C-20 methyl group with an iodine atom. Molecular dynamics simulations indicate that a significant increase in free energy is associated with the 13-cis conformation of 13-I-pR, consistent with our observation that the transient 13-I-pR conformational state is reached more rapidly. We conclude that although the conformational trajectory is accelerated, the major transient conformation of pR is unaffected by the substitution of an iodinated retinal chromophore.
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Affiliation(s)
- Erik Malmerberg
- Department of Chemistry, Biochemistry and Biophysics, University of Gothenburg, Gothenburg, Sweden
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15
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Hempelmann F, Hölper S, Verhoefen MK, Woerner AC, Köhler T, Fiedler SA, Pfleger N, Wachtveitl J, Glaubitz C. His75−Asp97 Cluster in Green Proteorhodopsin. J Am Chem Soc 2011; 133:4645-54. [DOI: 10.1021/ja111116a] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Franziska Hempelmann
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Soraya Hölper
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Mirka-Kristin Verhoefen
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Andreas C. Woerner
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Thomas Köhler
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Sarah-Anna Fiedler
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Nicole Pfleger
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Josef Wachtveitl
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Clemens Glaubitz
- Institute of Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance and ‡Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
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16
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Tamogami J, Kikukawa T, Miyauchi S, Muneyuki E, Kamo N. A Tin Oxide Transparent Electrode Provides the Means for Rapid Time-resolved pH Measurements: Application to Photoinduced Proton Transfer of Bacteriorhodopsin and Proteorhodopsin. Photochem Photobiol 2009; 85:578-89. [DOI: 10.1111/j.1751-1097.2008.00520.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Schäfer G, Shastri S, Verhoefen MK, Vogel V, Glaubitz C, Wachtveitl J, Mäntele W. Characterizing the Structure and Photocycle of PR 2D Crystals with CD and FTIR Spectroscopy. Photochem Photobiol 2009; 85:529-34. [DOI: 10.1111/j.1751-1097.2008.00491.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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Amsden JJ, Kralj JM, Bergo VB, Spudich EN, Spudich JL, Rothschild KJ. Different structural changes occur in blue- and green-proteorhodopsins during the primary photoreaction. Biochemistry 2008; 47:11490-8. [PMID: 18842006 DOI: 10.1021/bi800945t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We examine the structural changes during the primary photoreaction in blue-absorbing proteorhodopsin (BPR), a light-driven retinylidene proton pump, using low-temperature FTIR difference spectroscopy. Comparison of the light-induced BPR difference spectrum recorded at 80 K to that of green-absorbing proteorhodopsin (GPR) reveals that there are several differences in the BPR and GPR primary photoreactions despite the similar structure of the retinal chromophore and all-trans --> 13-cis isomerization. Strong bands near 1700 cm(-1) assigned previously to a change in hydrogen bonding of Asn230 in GPR are still present in BPR. However, additional bands in the same region are assigned on the basis of site-directed mutagenesis to changes occurring in Gln105. In the amide II region, bands are assigned on the basis of total (15)N labeling to structural changes of the protein backbone, although no such bands were previously observed for GPR. A band at 3642 cm(-1) in BPR, assigned to the OH stretching mode of a water molecule on the basis of H2(18)O substitution, appears at a different frequency than a band at 3626 cm(-1) previously assigned to a water molecule in GPR. However, the substitution of Gln105 for Leu105 in BPR leads to the appearance of both bands at 3642 and 3626 cm(-1), indicating the waters assigned in BPR and GPR exist in separate distinct locations and can coexist in the GPR-like Q105L mutant of BPR. These results indicate that there exist significant differences in the conformational changes occurring in these two types proteorhodopsin during the initial photoreaction despite their similar chromophore structures, which might reflect a different arrangement of water in the active site as well as substitution of a hydrophilic for hydrophobic residue at residue 105.
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Affiliation(s)
- Jason J Amsden
- Department of Physics, Photonics Center, and Molecular Biophysics Laboratory, Boston University, Boston, Massachusetts 02215, USA
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Initial reaction dynamics of proteorhodopsin observed by femtosecond infrared and visible spectroscopy. Biophys J 2008; 94:4796-807. [PMID: 18326639 DOI: 10.1529/biophysj.107.125484] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a comparative study using femtosecond pump/probe spectroscopy in the visible and infrared of the early photodynamics of solubilized proteorhodopsin (green absorbing variant) in D(2)O with deprotonated (pD 9.2) and protonated (pD 6.4) primary proton acceptor Asp-97. The vis-pump/vis-probe experiments show a kinetic isotope effect that is more pronounced for alkaline conditions, thus decreasing the previously reported pH-dependence of the primary reaction of proteorhodopsin in H(2)O. This points to a pH dependent H-bonding network in the binding pocket of proteorhodopsin, that directly influences the primary photo-induced dynamics. The vis-pump/IR-probe experiments were carried out in two different spectral regions and allowed to monitor the retinal C=C (1500 cm(-1)-1580 cm(-1)) and C=N stretching vibration as well as the amide I mode of the protein (1590 cm(-1)-1680 cm(-1)). Like the FTIR spectra of the K intermediate (PR(K)-PR difference spectra) in this spectral range, the kinetic parameters and also the quantum efficiency of photo-intermediate formation are found to be virtually independent of the pD value.
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Brown LS, Jung KH. Bacteriorhodopsin-like proteins of eubacteria and fungi: the extent of conservation of the haloarchaeal proton-pumping mechanism. Photochem Photobiol Sci 2006; 5:538-46. [PMID: 16761082 DOI: 10.1039/b514537f] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A stereotypical image of a retinal-binding proton pump derived from extensive studies of halobacterial ion-transporting and sensory rhodopsins is a fast-cycling protein which possesses two strategically placed carboxylic acids serving as proton donor and acceptor for the retinal Schiff base. We review recent biophysical and bioinformatic data on the novel eubacterial and eucaryotic rhodopsins to analyze the extent of conservation of the haloarchaeal mechanism of transmembrane proton transport. We show that only the most essential elements of the haloarchaeal proton-pumping machinery are conserved universally, and that a mere presence of these elements in primary structures does not guarantee the proton-pumping ability.
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Affiliation(s)
- Leonid S Brown
- Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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