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Timpmann K, Jalviste E, Chenchiliyan M, Kangur L, Jones MR, Freiberg A. High-pressure tuning of primary photochemistry in bacterial photosynthesis: membrane-bound versus detergent-isolated reaction centers. PHOTOSYNTHESIS RESEARCH 2020; 144:209-220. [PMID: 32095925 DOI: 10.1007/s11120-020-00724-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/11/2020] [Indexed: 06/10/2023]
Abstract
While photosynthesis thrives at close to normal pressures and temperatures, it is presently well known that life is similarly commonplace in the hostile environments of the deep seas as well as around hydrothermal vents. It is thus imperative to understand how key biological processes perform under extreme conditions of high pressures and temperatures. Herein, comparative steady-state and picosecond time-resolved spectroscopic studies were performed on membrane-bound and detergent-purified forms of a YM210W mutant reaction center (RC) from Rhodobacter sphaeroides under modulating conditions of high hydrostatic pressure applied at ambient temperature. A previously established breakage of the lone hydrogen bond formed between the RC primary donor and the protein scaffold was shown to take place in the membrane-bound RC at an almost 3 kbar higher pressure than in the purified RC, confirming the stabilizing role of the lipid environment for membrane proteins. The main change in the multi-exponential decay of excited primary donor emission across the experimental 10 kbar pressure range involved an over two-fold continuous acceleration, the kinetics becoming increasingly mono-exponential. The fastest component of the emission decay, thought to be largely governed by the rate of primary charge separation, was distinctly slower in the membrane-bound RC than in the purified RC. The change in character of the emission decay with pressure was explained by the contribution of charge recombination to emission decreasing with pressure as a result of an increasing free energy gap between the charge-separated and excited primary donor states. Finally, it was demonstrated that, in contrast to a long-term experimental paradigm, adding a combination of sodium ascorbate and phenazine methosulfate to the protein solution potentially distorts natural photochemistry in bacterial RCs.
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Affiliation(s)
- Kõu Timpmann
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu, 50411, Estonia
| | - Erko Jalviste
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu, 50411, Estonia
| | - Manoop Chenchiliyan
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu, 50411, Estonia
| | - Liina Kangur
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu, 50411, Estonia
| | - Michael R Jones
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Arvi Freiberg
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu, 50411, Estonia.
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, Tartu, 51010, Estonia.
- Estonian Academy of Sciences, Kohtu 6, Tallinn, 10130, Estonia.
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Jalviste E, Timpmann K, Chenchiliyan M, Kangur L, Jones MR, Freiberg A. High-Pressure Modulation of Primary Photosynthetic Reactions. J Phys Chem B 2020; 124:718-726. [PMID: 31917566 DOI: 10.1021/acs.jpcb.9b09342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photochemical charge separation is key to biological solar energy conversion. Although many features of this highly quantum-efficient process have been described, others remain poorly understood. Herein, ultrafast fluorescence barospectroscopy is used for the first time to obtain insights into the mechanism of primary charge separation in a YM210W mutant bacterial reaction center under novel surrounding modulating conditions. Over a range of applied hydrostatic pressures reaching 10 kbar, the rate of primary charge separation monotonously increased and that of the electron transfer to secondary acceptor decreased. While the inferred free energy gap for charge separation generally narrowed with increasing pressure, a pressure-induced break of a protein-cofactor hydrogen bond observed at ∼2 kbar significantly (by 219 cm-1 or 27 meV) increased this gap, resulting in a drop in fluorescence. The findings strongly favor a model for primary charge separation that incorporates charge recombination and restoration of the excited primary pair state, over a purely sequential model. We show that the main reason for the almost threefold acceleration of the primary electron transfer rate is the pressure-induced increase of the electronic coupling energy, rather than a change of activation energy. We also conclude that across all applied pressures, the primary electron transfer in the mutant reaction center studied can be considered nonadiabatic, normal region, and thermally activated.
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Affiliation(s)
- Erko Jalviste
- Institute of Physics , University of Tartu , W. Ostwald Str. 1 , Tartu 50411 , Estonia
| | - Kõu Timpmann
- Institute of Physics , University of Tartu , W. Ostwald Str. 1 , Tartu 50411 , Estonia
| | - Manoop Chenchiliyan
- Institute of Physics , University of Tartu , W. Ostwald Str. 1 , Tartu 50411 , Estonia
| | - Liina Kangur
- Institute of Physics , University of Tartu , W. Ostwald Str. 1 , Tartu 50411 , Estonia
| | - Michael R Jones
- School of Biochemistry , University of Bristol , Biomedical Sciences Building, University Walk , Bristol BS8 1TD , U.K
| | - Arvi Freiberg
- Institute of Physics , University of Tartu , W. Ostwald Str. 1 , Tartu 50411 , Estonia.,Institute of Molecular and Cell Biology , University of Tartu , Riia 23 , Tartu 51010 , Estonia.,Estonian Academy of Sciences , Kohtu 6 , 10130 Tallinn , Estonia
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In situ spectroelectrochemical investigation of a biophotoelectrode based on photoreaction centers embedded in a redox hydrogel. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2019.135190] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Farooq S, Chmeliov J, Wientjes E, Koehorst R, Bader A, Valkunas L, Trinkunas G, van Amerongen H. Dynamic feedback of the photosystem II reaction centre on photoprotection in plants. NATURE PLANTS 2018; 4:225-231. [PMID: 29610535 DOI: 10.1038/s41477-018-0127-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/01/2018] [Indexed: 05/08/2023]
Abstract
Photosystem II of higher plants is protected against light damage by thermal dissipation of excess excitation energy, a process that can be monitored through non-photochemical quenching of chlorophyll fluorescence. When the light intensity is lowered, non-photochemical quenching largely disappears on a time scale ranging from tens of seconds to many minutes. With the use of picosecond fluorescence spectroscopy, we demonstrate that one of the underlying mechanisms is only functional when the reaction centre of photosystem II is closed, that is when electron transfer is blocked and the risk of photodamage is high. This is accompanied by the appearance of a long-wavelength fluorescence band. As soon as the reaction centre reopens, this quenching, together with the long-wavelength fluorescence, disappears instantaneously. This allows plants to maintain a high level of photosynthetic efficiency even in dangerous high-light conditions.
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Affiliation(s)
- Shazia Farooq
- Laboratory of Biophysics, Wageningen University and Research, Wageningen, the Netherlands
| | - Jevgenij Chmeliov
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Vilnius, Lithuania
- Department of Molecular Compound Physics, Centre for Physical Sciences and Technology, Vilnius, Lithuania
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University and Research, Wageningen, the Netherlands
| | - Rob Koehorst
- Laboratory of Biophysics, Wageningen University and Research, Wageningen, the Netherlands
| | - Arjen Bader
- Laboratory of Biophysics, Wageningen University and Research, Wageningen, the Netherlands
- MicroSpectroscopy Research Facility, Wageningen University and Research, Wageningen, the Netherlands
| | - Leonas Valkunas
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Vilnius, Lithuania
- Department of Molecular Compound Physics, Centre for Physical Sciences and Technology, Vilnius, Lithuania
| | - Gediminas Trinkunas
- Department of Molecular Compound Physics, Centre for Physical Sciences and Technology, Vilnius, Lithuania
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University and Research, Wageningen, the Netherlands.
- MicroSpectroscopy Research Facility, Wageningen University and Research, Wageningen, the Netherlands.
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Lambrev PH, Miloslavina Y, Jahns P, Holzwarth AR. On the relationship between non-photochemical quenching and photoprotection of Photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:760-9. [PMID: 22342615 DOI: 10.1016/j.bbabio.2012.02.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 01/31/2012] [Accepted: 02/02/2012] [Indexed: 11/17/2022]
Abstract
Non-photochemical quenching (NPQ) of chlorophyll fluorescence is thought to be an indicator of an essential regulation and photoprotection mechanism against high-light stress in photosynthetic organisms. NPQ is typically characterized by modulated pulse fluorometry and it is often assumed implicitly to be a good proxy for the actual physiological photoprotection capacity of the organism. Using the results of previously published ultrafast fluorescence measurements on intact leaves of w.t. and mutants of Arabidopsis (Holzwarth et al. 2009) we have developed exact relationships for the fluorescence quenching and the corresponding Photosystem II acceptor side photoprotection effects under NPQ conditions. The approach based on the exciton-radical pair equilibrium model assumes that photodamage results from triplet states generated in the reaction center. The derived relationships allow one to distinguish and determine the individual and combined quenching as well as photoprotection contributions of each of the multiple NPQ mechanisms. Our analysis shows inter alia that quenching and photoprotection are not linearly related and that antenna detachment, which can be identified with the so-called qE mechanism, contributes largely to the measured fluorescence quenching but does not correspond to the most efficient photoprotective response. Conditions are formulated which allow simultaneously the maximal photosynthetic electron flow as well as maximal acceptor side photoprotection. It is shown that maximal photoprotection can be achieved if NPQ is regulated in such a way that PSII reaction centers are open under given light conditions. The results are of fundamental importance for a proper interpretation of the physiological relevance of fluorescence-based NPQ data.
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Affiliation(s)
- Petar H Lambrev
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstr. 34-36, 45470 Mülheim a.d. Ruhr, Germany
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Bixon M, Jortner J. Electron Transfer-from Isolated Molecules to Biomolecules. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141656.ch3] [Citation(s) in RCA: 232] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Determination of Q(A)-content in bacterial reaction centers: an indispensable requirement for quantifying B-branch charge separation. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1412:273-81. [PMID: 10482789 DOI: 10.1016/s0005-2728(99)00070-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have been able to determine the occupancy of the quinone site at the A-branch (Q(A)) of a reaction center preparation with an accuracy of 2%. This is achieved by accumulating the P(+)Q(-)(A) state after multiple actinic excitation and monitoring the extent of the 30 ms ground state bleaching. This bleaching is corrected for deviations from complete saturation due to competing charge separation to the B-branch. On the other hand, knowledge of the Q(A) content is indispensable for determining the yield of B-branch charge separation from nanosecond transients associated with the recombination of P(+)H(-)(B), which have to be corrected for the nanosecond signal originating from P(+)H(-)(A) of RCs having lost Q(A).
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Novel multipulse saturation spectroscopy for quantum yield determination of charge separation in modified photosynthetic reaction centers. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00461-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ogrodnik A, Hartwich G, Lossau H, Michel-Beyerle M. Dispersive charge separation and conformational cooling of P+HA− in reaction centers of Rb. sphaeroides R26: a spontaneous emission study. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00037-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Hartwich G, Lossau H, Michel-Beyerle ME, Ogrodnik A. Nonexponential Fluorescence Decay in Reaction Centers of Rhodobacter sphaeroides Reflecting Dispersive Charge Separation up to 1 ns. J Phys Chem B 1998. [DOI: 10.1021/jp973472h] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- G. Hartwich
- Institut für Physikalische und Theoretische Chemie, TU München, Lichtenbergstrasse 4, D-85747 Garching, Germany
| | - H. Lossau
- Institut für Physikalische und Theoretische Chemie, TU München, Lichtenbergstrasse 4, D-85747 Garching, Germany
| | - M. E. Michel-Beyerle
- Institut für Physikalische und Theoretische Chemie, TU München, Lichtenbergstrasse 4, D-85747 Garching, Germany
| | - A. Ogrodnik
- Institut für Physikalische und Theoretische Chemie, TU München, Lichtenbergstrasse 4, D-85747 Garching, Germany
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