1
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Kirpich JS, Luo L, Nelson MR, Agarwala N, Xu W, Hastings G. Is the A -1 Pigment in Photosystem I Part of P700? A (P700 +-P700) FTIR Difference Spectroscopy Study of A -1 Mutants. Int J Mol Sci 2024; 25:4839. [PMID: 38732056 PMCID: PMC11084411 DOI: 10.3390/ijms25094839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 04/24/2024] [Accepted: 04/25/2024] [Indexed: 05/13/2024] Open
Abstract
The involvement of the second pair of chlorophylls, termed A-1A and A-1B, in light-induced electron transfer in photosystem I (PSI) is currently debated. Asparagines at PsaA600 and PsaB582 are involved in coordinating the A-1B and A-1A pigments, respectively. Here we have mutated these asparagine residues to methionine in two single mutants and a double mutant in PSI from Synechocystis sp. PCC 6803, which we term NA600M, NB582M, and NA600M/NB582M mutants. (P700+-P700) FTIR difference spectra (DS) at 293 K were obtained for the wild-type and the three mutant PSI samples. The wild-type and mutant FTIR DS differ considerably. This difference indicates that the observed changes in the (P700+-P700) FTIR DS cannot be due to only the PA and PB pigments of P700. Comparison of the wild-type and mutant FTIR DS allows the assignment of different features to both A-1 pigments in the FTIR DS for wild-type PSI and assesses how these features shift upon cation formation and upon mutation. While the exact role the A-1 pigments play in the species we call P700 is unclear, we demonstrate that the vibrational modes of the A-1A and A-1B pigments are modified upon P700+ formation. Previously, we showed that the A-1 pigments contribute to P700 in green algae. In this manuscript, we demonstrate that this is also the case in cyanobacterial PSI. The nature of the mutation-induced changes in algal and cyanobacterial PSI is similar and can be considered within the same framework, suggesting a universality in the nature of P700 in different photosynthetic organisms.
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Affiliation(s)
- Julia S. Kirpich
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
| | - Lujun Luo
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA
| | - Michael R. Nelson
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
| | - Neva Agarwala
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
| | - Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA
| | - Gary Hastings
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
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2
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Luo L, Martin AP, Tandoh EK, Chistoserdov A, Slipchenko LV, Savikhin S, Xu W. Impact of Peripheral Hydrogen Bond on Electronic Properties of the Primary Acceptor Chlorophyll in the Reaction Center of Photosystem I. Int J Mol Sci 2024; 25:4815. [PMID: 38732034 PMCID: PMC11084960 DOI: 10.3390/ijms25094815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 04/18/2024] [Accepted: 04/24/2024] [Indexed: 05/13/2024] Open
Abstract
Photosystem I (PS I) is a photosynthetic pigment-protein complex that absorbs light and uses the absorbed energy to initiate electron transfer. Electron transfer has been shown to occur concurrently along two (A- and B-) branches of reaction center (RC) cofactors. The electron transfer chain originates from a special pair of chlorophyll a molecules (P700), followed by two chlorophylls and one phylloquinone in each branch (denoted as A-1, A0, A1, respectively), converging in a single iron-sulfur complex Fx. While there is a consensus that the ultimate electron donor-acceptor pair is P700+A0-, the involvement of A-1 in electron transfer, as well as the mechanism of the very first step in the charge separation sequence, has been under debate. To resolve this question, multiple groups have targeted electron transfer cofactors by site-directed mutations. In this work, the peripheral hydrogen bonds to keto groups of A0 chlorophylls have been disrupted by mutagenesis. Four mutants were generated: PsaA-Y692F; PsaB-Y667F; PsaB-Y667A; and a double mutant PsaA-Y692F/PsaB-Y667F. Contrary to expectations, but in agreement with density functional theory modeling, the removal of the hydrogen bond by Tyr → Phe substitution was found to have a negligible effect on redox potentials and optical absorption spectra of respective chlorophylls. In contrast, Tyr → Ala substitution was shown to have a fatal effect on the PS I function. It is thus inferred that PsaA-Y692 and PsaB-Y667 residues have primarily structural significance, and their ability to coordinate respective chlorophylls in electron transfer via hydrogen bond plays a minor role.
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Affiliation(s)
- Lujun Luo
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA; (L.L.)
| | - Antoine P. Martin
- Department of Physics, Purdue University, West Lafayette, IN 47907, USA
| | - Elijah K. Tandoh
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA; (L.L.)
| | - Andrei Chistoserdov
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70504, USA
| | | | - Sergei Savikhin
- Department of Physics, Purdue University, West Lafayette, IN 47907, USA
| | - Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA; (L.L.)
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3
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Reiter S, Kiss FL, Hauer J, de Vivie-Riedle R. Thermal site energy fluctuations in photosystem I: new insights from MD/QM/MM calculations. Chem Sci 2023; 14:3117-3131. [PMID: 36970098 PMCID: PMC10034153 DOI: 10.1039/d2sc06160k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Cyanobacterial photosystem I (PSI) is one of the most efficient photosynthetic machineries found in nature. Due to the large scale and complexity of the system, the energy transfer mechanism from the antenna complex to the reaction center is still not fully understood. A central element is the accurate evaluation of the individual chlorophyll excitation energies (site energies). Such an evaluation must include a detailed treatment of site specific environmental influences on structural and electrostatic properties, but also their evolution in the temporal domain, because of the dynamic nature of the energy transfer process. In this work, we calculate the site energies of all 96 chlorophylls in a membrane-embedded model of PSI. The employed hybrid QM/MM approach using the multireference DFT/MRCI method in the QM region allows to obtain accurate site energies under explicit consideration of the natural environment. We identify energy traps and barriers in the antenna complex and discuss their implications for energy transfer to the reaction center. Going beyond previous studies, our model also accounts for the molecular dynamics of the full trimeric PSI complex. Via statistical analysis we show that the thermal fluctuations of single chlorophylls prevent the formation of a single prominent energy funnel within the antenna complex. These findings are also supported by a dipole exciton model. We conclude that energy transfer pathways may form only transiently at physiological temperatures, as thermal fluctuations overcome energy barriers. The set of site energies provided in this work sets the stage for theoretical and experimental studies on the highly efficient energy transfer mechanisms in PSI.
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Affiliation(s)
- Sebastian Reiter
- Department of Chemistry, Ludwig-Maximilians-Universität München Butenandtstr. 11 81377 Munich Germany
| | - Ferdinand L Kiss
- Department of Chemistry, Ludwig-Maximilians-Universität München Butenandtstr. 11 81377 Munich Germany
| | - Jürgen Hauer
- Department of Chemistry, Technical University of Munich Lichtenbergstr. 4, Garching 85747 Germany
| | - Regina de Vivie-Riedle
- Department of Chemistry, Ludwig-Maximilians-Universität München Butenandtstr. 11 81377 Munich Germany
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4
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Zhang S, Zou B, Cao P, Su X, Xie F, Pan X, Li M. Structural insights into photosynthetic cyclic electron transport. MOLECULAR PLANT 2023; 16:187-205. [PMID: 36540023 DOI: 10.1016/j.molp.2022.12.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/17/2022] [Accepted: 12/18/2022] [Indexed: 06/17/2023]
Abstract
During photosynthesis, light energy is utilized to drive sophisticated biochemical chains of electron transfers, converting solar energy into chemical energy that feeds most life on earth. Cyclic electron transfer/flow (CET/CEF) plays an essential role in efficient photosynthesis, as it balances the ATP/NADPH ratio required in various regulatory and metabolic pathways. Photosystem I, cytochrome b6f, and NADH dehydrogenase (NDH) are large multisubunit protein complexes embedded in the thylakoid membrane of the chloroplast and key players in NDH-dependent CEF pathway. Furthermore, small mobile electron carriers serve as shuttles for electrons between these membrane protein complexes. Efficient electron transfer requires transient interactions between these electron donors and acceptors. Structural biology has been a powerful tool to advance our knowledge of this important biological process. A number of structures of the membrane-embedded complexes, soluble electron carrier proteins, and transient complexes composed of both have now been determined. These structural data reveal detailed interacting patterns of these electron donor-acceptor pairs, thus allowing us to visualize the different parts of the electron transfer process. This review summarizes the current state of structural knowledge of three membrane complexes and their interaction patterns with mobile electron carrier proteins.
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Affiliation(s)
- Shumeng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Baohua Zou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Peng Cao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Xiaodong Su
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Fen Xie
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Xiaowei Pan
- College of Life Science, Capital Normal University, Beijing, China
| | - Mei Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
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5
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Cherepanov DA, Semenov AY, Mamedov MD, Aybush AV, Gostev FE, Shelaev IV, Shuvalov VA, Nadtochenko VA. Current state of the primary charge separation mechanism in photosystem I of cyanobacteria. Biophys Rev 2022; 14:805-820. [PMID: 36124265 PMCID: PMC9481807 DOI: 10.1007/s12551-022-00983-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/10/2022] [Indexed: 11/24/2022] Open
Abstract
This review analyzes new data on the mechanism of ultrafast reactions of primary charge separation in photosystem I (PS I) of cyanobacteria obtained in the last decade by methods of femtosecond absorption spectroscopy. Cyanobacterial PS I from many species harbours 96 chlorophyll a (Chl a) molecules, including six specialized Chls denoted Chl1A/Chl1B (dimer P700, or PAPB), Chl2A/Chl2B, and Chl3A/Chl3B arranged in two branches, which participate in electron transfer reactions. The current data indicate that the primary charge separation occurs in a symmetric exciplex, where the special pair P700 is electronically coupled to the symmetrically located monomers Chl2A and Chl2B, which can be considered together as a symmetric exciplex Chl2APAPBChl2B with the mixed excited (Chl2APAPBChl2B)* and two charge-transfer states P700 +Chl2A - and P700 +Chl2B -. The redistribution of electrons between the branches in favor of the A-branch occurs after reduction of the Chl2A and Chl2B monomers. The formation of charge-transfer states and the symmetry breaking mechanisms were clarified by measuring the electrochromic Stark shift of β-carotene and the absorption dynamics of PS I complexes with the genetically altered Chl 2B or Chl 2A monomers. The review gives a brief description of the main methods for analyzing data obtained using femtosecond absorption spectroscopy. The energy levels of excited and charge-transfer intermediates arising in the cyanobacterial PS I are critically analyzed.
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Affiliation(s)
- Dmitry A. Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
| | - Alexey Yu Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
- A.N. Belozersky Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, 119992 Leninskye gory 1 building, 40 Moscow, Russia
| | - Mahir D. Mamedov
- A.N. Belozersky Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, 119992 Leninskye gory 1 building, 40 Moscow, Russia
| | - Arseniy V. Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
| | - Fedor E. Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
| | - Ivan V. Shelaev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
| | - Vladimir A. Shuvalov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
| | - Victor A. Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991, Kosygina Street 1, Moscow, Russia
- Department of Chemistry, Lomonosov Moscow State University, 119991, Leninskiye Gory 1-3, Moscow, Russia
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6
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Keable SM, Kölsch A, Simon PS, Dasgupta M, Chatterjee R, Subramanian SK, Hussein R, Ibrahim M, Kim IS, Bogacz I, Makita H, Pham CC, Fuller FD, Gul S, Paley D, Lassalle L, Sutherlin KD, Bhowmick A, Moriarty NW, Young ID, Blaschke JP, de Lichtenberg C, Chernev P, Cheah MH, Park S, Park G, Kim J, Lee SJ, Park J, Tono K, Owada S, Hunter MS, Batyuk A, Oggenfuss R, Sander M, Zerdane S, Ozerov D, Nass K, Lemke H, Mankowsky R, Brewster AS, Messinger J, Sauter NK, Yachandra VK, Yano J, Zouni A, Kern J. Room temperature XFEL crystallography reveals asymmetry in the vicinity of the two phylloquinones in photosystem I. Sci Rep 2021; 11:21787. [PMID: 34750381 PMCID: PMC8575901 DOI: 10.1038/s41598-021-00236-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 09/02/2021] [Indexed: 11/09/2022] Open
Abstract
Photosystem I (PS I) has a symmetric structure with two highly similar branches of pigments at the center that are involved in electron transfer, but shows very different efficiency along the two branches. We have determined the structure of cyanobacterial PS I at room temperature (RT) using femtosecond X-ray pulses from an X-ray free electron laser (XFEL) that shows a clear expansion of the entire protein complex in the direction of the membrane plane, when compared to previous cryogenic structures. This trend was observed by complementary datasets taken at multiple XFEL beamlines. In the RT structure of PS I, we also observe conformational differences between the two branches in the reaction center around the secondary electron acceptors A1A and A1B. The π-stacked Phe residues are rotated with a more parallel orientation in the A-branch and an almost perpendicular confirmation in the B-branch, and the symmetry breaking PsaB-Trp673 is tilted and further away from A1A. These changes increase the asymmetry between the branches and may provide insights into the preferential directionality of electron transfer.
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Affiliation(s)
- Stephen M Keable
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Adrian Kölsch
- Institut für Biologie, Humboldt-Universität Zu Berlin, 10115, Berlin, Germany
| | - Philipp S Simon
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Medhanjali Dasgupta
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | | | - Rana Hussein
- Institut für Biologie, Humboldt-Universität Zu Berlin, 10115, Berlin, Germany
| | - Mohamed Ibrahim
- Institut für Biologie, Humboldt-Universität Zu Berlin, 10115, Berlin, Germany
| | - In-Sik Kim
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Isabel Bogacz
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hiroki Makita
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Cindy C Pham
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Franklin D Fuller
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Daniel Paley
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Louise Lassalle
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kyle D Sutherlin
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Asmit Bhowmick
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Nigel W Moriarty
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Iris D Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA, 94158, USA
| | - Johannes P Blaschke
- National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Casper de Lichtenberg
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, 75237, Uppsala, Sweden.,Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), 90187, Umeå, Sweden
| | - Petko Chernev
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, 75237, Uppsala, Sweden
| | - Mun Hon Cheah
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, 75237, Uppsala, Sweden
| | - Sehan Park
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Korea
| | - Gisu Park
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Korea
| | - Jangwoo Kim
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Korea
| | - Sang Jae Lee
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Korea
| | - Jaehyun Park
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Korea
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5148, Japan
| | - Shigeki Owada
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5148, Japan
| | - Mark S Hunter
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Alexander Batyuk
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | | | | | | | | | - Karol Nass
- Paul Scherrer Institut, 5232, Villigen, Switzerland
| | - Henrik Lemke
- Paul Scherrer Institut, 5232, Villigen, Switzerland
| | | | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Johannes Messinger
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, 75237, Uppsala, Sweden
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Vittal K Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Athina Zouni
- Institut für Biologie, Humboldt-Universität Zu Berlin, 10115, Berlin, Germany
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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7
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Cherepanov DA, Shelaev IV, Gostev FE, Nadtochenko VA, Xu W, Golbeck JH, Semenov AY. Symmetry breaking in photosystem I: ultrafast optical studies of variants near the accessory chlorophylls in the A- and B-branches of electron transfer cofactors. Photochem Photobiol Sci 2021; 20:1209-1227. [PMID: 34478050 DOI: 10.1007/s43630-021-00094-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 08/18/2021] [Indexed: 11/25/2022]
Abstract
Femtosecond absorption spectroscopy of Photosystem I (PS I) complexes from the cyanobacterium Synechocystis sp. PCC 6803 was carried out on three pairs of complementary amino acid substitutions located near the second pair of chlorophyll molecules Chl2A and Chl2B (also termed A-1A and A-1B). The absorption dynamics at delays of 0.1-500 ps were analyzed by decomposition into discrete decay-associated spectra and continuously distributed exponential components. The multi-exponential deconvolution of the absorption changes revealed that the electron transfer reactions in the PsaA-N600M, PsaA-N600H, and PsaA-N600L variants near the B-branch of cofactors are similar to those of the wild type, while the PsaB-N582M, PsaB-N582H, and PsaB-N582L variants near the A-branch of cofactors cause significant alterations of the photochemical processes, making them heterogeneous and poorly described by a discrete exponential kinetic model. A redistribution of the unpaired electron between the second and the third monomers Chl2A/Chl2B and Chl3A/Chl3B was identified in the time range of 9-20 ps, and the subsequent reduction of A1 was identified in the time range of 24-70 ps. In the PsaA-N600L and PsaB-N582H/L variants, the reduction of A1 occurred with a decreased quantum yield of charge separation. The decreased quantum yield correlates with a slowing of the phylloquinone A0 → A1 reduction, but not with the initial transient spectra measured at the shortest time delay. The results support a branch competition model, where the electron is sheared between Chl2A-Chl3A and Chl2B-Chl3B cofactors before its transfer to phylloquinone in either A1A or A1B sites.
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Affiliation(s)
- Dmitry A Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina St. 4, Moscow, 117977, Russian Federation.
| | - Ivan V Shelaev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina St. 4, Moscow, 117977, Russian Federation
| | - Fedor E Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina St. 4, Moscow, 117977, Russian Federation
| | - Victor A Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina St. 4, Moscow, 117977, Russian Federation.,Department of Chemistry, Lomonosov Moscow State University, Leninskiye Gory 1-3, Moscow, 119991, Russian Federation
| | - Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16801, USA.,Department of Chemistry, The Pennsylvania State University, University Park, PA, 16801, USA
| | - Alexey Yu Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina St. 4, Moscow, 117977, Russian Federation.,A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, Moscow, 119992, Russian Federation
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8
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Cherepanov DA, Shelaev IV, Gostev FE, Petrova A, Aybush AV, Nadtochenko VA, Xu W, Golbeck JH, Semenov AY. Primary charge separation within the structurally symmetric tetrameric Chl 2AP AP BChl 2B chlorophyll exciplex in photosystem I. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2021; 217:112154. [PMID: 33636482 DOI: 10.1016/j.jphotobiol.2021.112154] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/05/2021] [Accepted: 02/12/2021] [Indexed: 12/01/2022]
Abstract
In Photosystem I (PS I), the role of the accessory chlorophyll (Chl) molecules, Chl2A and Chl2B (also termed A-1A and A-1B), which are directly adjacent to the special pair P700 and fork into the A- and B-branches of electron carriers, is incompletely understood. In this work, the Chl2A and Chl2B transient absorption ΔA0(λ) at a time delay of 100 fs was identified by ultrafast pump-probe spectroscopy in three pairs of PS I complexes from Synechocystis sp. PCC 6803 with residues PsaA-N600 or PsaB-N582 (which ligate Chl2B or Chl2A through a H2O molecule) substituted by Met, His, and Leu. The ΔA0(λ) spectra were quantified using principal component analysis, the main component of which was interpreted as a mutation-induced shift of the equilibrium between the excited state of primary donor P700⁎ and the primary charge-separated state P700+Chl2-. This equilibrium is shifted to the charge-separated state in wild-type PS I and to the excited P700 in the PS I complexes with the substituted ligands to the Chl2A and Chl2B monomers. The results can be rationalized within the framework of an adiabatic model in which the P700 is electronically coupled with the symmetrically arranged monomers Chl2A and Chl2B; such a structure can be considered a symmetric tetrameric exciplex Chl2APAPBChl2B, in which the excited state (Chl2APAPBChl2B)* is mixed with two charge-transfer states P700+Chl2A- and P700+Chl2B-. The electron redistribution between the two branches in favor of the A-branch apparently takes place in the picosecond time scale after reduction of the Chl2A and Chl2B monomers.
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Affiliation(s)
- Dmitry A Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Kosygina st., 4, Russia.
| | - Ivan V Shelaev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Kosygina st., 4, Russia
| | - Fedor E Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Kosygina st., 4, Russia
| | - Anastasia Petrova
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Leninskie gory, 1, Building 40, Russia
| | - Arseniy V Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Kosygina st., 4, Russia
| | - Victor A Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Kosygina st., 4, Russia; Department of Chemistry, Lomonosov Moscow State University, Leninskiye Gory 1-3, Moscow 119991, Russian Federation
| | - Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16801, USA; Department of Chemistry, The Pennsylvania State University, University Park, PA 16801, USA
| | - Alexey Yu Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Kosygina st., 4, Russia; A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Leninskie gory, 1, Building 40, Russia
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9
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Chestnut MM, Milikisiyants S, Chatterjee R, Kern J, Smirnov AI. Electronic Structure of the Primary Electron Donor P700+• in Photosystem I Studied by Multifrequency HYSCORE Spectroscopy at X- and Q-Band. J Phys Chem B 2021; 125:36-48. [PMID: 33356277 DOI: 10.1021/acs.jpcb.0c09000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The primary electron donor P700 of the photosystem I (PSI) is a heterodimer consisting of two chlorophyll molecules. A series of electron-transfer events immediately following the initial light excitation leads to a stabilization of the positive charge by its cation radical form, P700+•. The electronic structure of P700+• and, in particular, its asymmetry with respect to the two chlorophyll monomers is of fundamental interest and is not fully understood up to this date. Here, we apply multifrequency X- (9 GHz) and Q-band (35 GHz) hyperfine sublevel correlation (HYSCORE) spectroscopy to investigate the electron spin density distribution in the cation radical P700+• of PSI from a thermophilic cyanobacterium Thermosynechococcus elongatus. Six 14N and two 1H distinct nuclei have been resolved in the HYSCORE spectra and parameters of the corresponding nuclear hyperfine and quadrupolar hyperfine interactions were obtained by combining the analysis of HYSCORE spectral features with direct numerical simulations. Based on a close similarity of the nuclear quadrupole tensor parameters, all of the resolved 14N nuclei were assigned to six out of total eight available pyrrole ring nitrogen atoms (i.e., four in each of the chlorophylls), providing direct evidence of spin density delocalization over the both monomers in the heterodimer. Using the obtained experimental values of the 14N electron-nuclear hyperfine interaction parameters, the upper limit of the electron spin density asymmetry parameter is estimated as RA/Bupper = 7.7 ± 0.5, while a tentative assignment of 14N observed in the HYSCORE spectra yields RB/A = 3.1 ± 0.5.
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Affiliation(s)
- Melanie M Chestnut
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
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10
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Cherepanov DA, Shelaev IV, Gostev FE, Aybush AV, Mamedov MD, Shuvalov VA, Semenov AY, Nadtochenko VA. Generation of ion-radical chlorophyll states in the light-harvesting antenna and the reaction center of cyanobacterial photosystem I. PHOTOSYNTHESIS RESEARCH 2020; 146:55-73. [PMID: 32144697 DOI: 10.1007/s11120-020-00731-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/24/2020] [Indexed: 05/09/2023]
Abstract
The energy and charge-transfer processes in photosystem I (PS I) complexes isolated from cyanobacteria Thermosynechococcus elongatus and Synechocystis sp. PCC 6803 were investigated by pump-to-probe femtosecond spectroscopy. The formation of charge-transfer (CT) states in excitonically coupled chlorophyll a complexes (exciplexes) was monitored by measuring the electrochromic shift of β-carotene in the spectral range 500-510 nm. The excitation of high-energy chlorophyll in light-harvesting antenna of both species was not accompanied by immediate appearance of an electrochromic shift. In PS I from T. elongatus, the excitation of long-wavelength chlorophyll (LWC) caused a pronounced electrochromic effect at 502 nm assigned to the appearance of CT states of chlorophyll exciplexes. The formation of ion-radical pair P700+A1- at 40 ps was limited by energy transfer from LWC to the primary donor P700 and accompanied by carotenoid bleach at 498 nm. In PS I from Synechocystis 6803, the excitation at 720 nm produced an immediate bidentate bleach at 690/704 nm and synchronous carotenoid response at 508 nm. The bidentate bleach was assigned to the formation of primary ion-radical state PB+Chl2B-, where negative charge is localized predominantly at the accessory chlorophyll molecule in the branch B, Chl2B. The following decrease of carotenoid signal at ~ 5 ps was ascribed to electron transfer to the more distant molecule Chl3B. The reduction of phylloquinone in the sites A1A and A1B was accompanied by a synchronous blue-shift of the carotenoid response to 498 nm, pointing to fast redistribution of unpaired electron between two branches in favor of the state PB+A1A-.
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Affiliation(s)
- Dmitry A Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia.
| | - Ivan V Shelaev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Fedor E Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Arseniy V Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Mahir D Mamedov
- A.N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, Kosygina st., 4, Moscow, Russia, 117991
| | - Vladimir A Shuvalov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
- A.N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, Kosygina st., 4, Moscow, Russia, 117991
- Institute of Basic Biological Problems, Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Alexey Yu Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
- A.N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, Kosygina st., 4, Moscow, Russia, 117991
| | - Victor A Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
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11
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Orf GS, Redding KE. Perturbation of the primary acceptor chlorophyll site in the heliobacterial reaction center by coordinating amino acid substitution. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148324. [PMID: 33039349 DOI: 10.1016/j.bbabio.2020.148324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 11/19/2022]
Abstract
All known Type I photochemical reaction center protein complexes contain a form of the pigment chlorophyll a in their primary electron acceptor site (termed ec3). In the reaction center from the primitive heliobacteria (HbRC), all of the pigment cofactors are bacteriochlorophyll g except in the ec3 sites, which contain 81-hydroxychlorophyll a. To explore the energetic flexibility of this site, we performed site-directed mutagenesis on two of the amino acids of the PshA core polypeptide responsible for coordinating the 81-hydroxychlorophyll a. These two amino acids are serine-545, which coordinates the central Mg(II) through an intermediary water molecule, and serine-553, which participates in a hydrogen bond with the 131-keto O atom. Mutagenesis of serine-545 to histidine (S545H) changes how the chlorophyll's central Mg(II) is coordinated, with the result of decreasing the chlorophyll's site energy. Mutagenesis of serine-545 to methionine (S545M), which was made to mimic the ec3 site of Photosystem I, abolishes chlorophyll binding and charge separation altogether. Mutagenesis of serine-553 to alanine (S553A) removes the aforementioned hydrogen bond, increasing the site energy of the chlorophyll. In the S545H and S553A mutants, the forward and reverse electron transfer rates from ec3 are both faster. This coincides with a decrease in both the quantum yield of initial charge separation and the overall photochemical quantum yield. Taken together, these data indicate that wild-type HbRC is optimized for overall photochemical efficiency, rather than just for maximizing the forward electron transfer rate. The necessity for a chlorophyll a derivative at the ec3 site is also discussed.
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Affiliation(s)
- Gregory S Orf
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Kevin E Redding
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
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12
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Evidence that chlorophyll f functions solely as an antenna pigment in far-red-light photosystem I from Fischerella thermalis PCC 7521. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148184. [PMID: 32179058 DOI: 10.1016/j.bbabio.2020.148184] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 02/21/2020] [Accepted: 03/09/2020] [Indexed: 11/20/2022]
Abstract
The Photosystem I (PSI) reaction center in cyanobacteria is comprised of ~96 chlorophyll (Chl) molecules, including six specialized Chl molecules denoted Chl1A/Chl1B (P700), Chl2A/Chl2B, and Chl3A/Chl3B that are arranged in two branches and function in primary charge separation. It has recently been proposed that PSI from Chroococcidiopsis thermalis (Nürnberg et al. (2018) Science 360, 1210-1213) and Fischerella thermalis PCC 7521 (Hastings et al. (2019) Biochim. Biophys. Acta 1860, 452-460) contain Chl f in the positions Chl2A/Chl2B. We tested this proposal by exciting RCs from white-light grown (WL-PSI) and far-red light grown (FRL-PSI) F. thermalis PCC 7521 with femtosecond pulses and analyzing the optical dynamics. If Chl f were in the position Chl2A/Chl2B in FRL-PSI, excitation at 740 nm should have produced the charge-separated state P700+A0- followed by electron transfer to A1 with a τ of ≤25 ps. Instead, it takes ~230 ps for the charge-separated state to develop because the excitation migrates uphill from Chl f in the antenna to the trapping center. Further, we observe a strong electrochromic shift at 685 nm in the final P700+A1- spectrum that can only be explained if Chl a is in the positions Chl2A/Chl2B. Similar arguments rule out the presence of Chl f in the positions Chl3A/Chl3B; hence, Chl f is likely to function solely as an antenna pigment in FRL-PSI. We additionally report the presence of an excitonically coupled homo- or heterodimer of Chl f absorbing around 790 nm that is kinetically independent of the Chl f population that absorbs around 740 nm.
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13
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Cherepanov DA, Brady NG, Shelaev IV, Nguyen J, Gostev FE, Mamedov MD, Nadtochenko VA, Bruce BD. PSI-SMALP, a Detergent-free Cyanobacterial Photosystem I, Reveals Faster Femtosecond Photochemistry. Biophys J 2020; 118:337-351. [PMID: 31882247 PMCID: PMC6976803 DOI: 10.1016/j.bpj.2019.11.3391] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/17/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022] Open
Abstract
Cyanobacterial photosystem I (PSI) functions as a light-driven cyt c6-ferredoxin/oxidoreductase located in the thylakoid membrane. In this work, the energy and charge transfer processes in PSI complexes isolated from Thermosynechococcus elongatus via conventional n-dodecyl-β-D-maltoside solubilization (DM-PSI) and a, to our knowledge, new detergent-free method using styrene-maleic acid copolymers (SMA-PSI) have been investigated by pump-to-probe femtosecond laser spectroscopy. In DM-PSI preparations excited at 740 nm, the excitation remained localized on the long-wavelength chlorophyll forms within 0.1-20 ps and revealed little or no charge separation and oxidation of the special pair, P700. The formation of ion-radical pair P700+A1- occurred with a characteristic time of 36 ps, being kinetically controlled by energy transfer from the long-wavelength chlorophyll to P700. Quite surprisingly, the detergent-free SMA-PSI complexes upon excitation by these long-wave pulses undergo an ultrafast (<100 fs) charge separation in ∼45% of particles. In the remaining complexes (∼55%), the energy transfer to P700 occurred at ∼36 ps, similar to the DM-PSI. Both isolation methods result in a trimeric form of PSI, yet the SMA-PSI complexes display a heterogenous kinetic behavior. The much faster rate of charge separation suggests the existence of an ultrafast pathway for charge separation in the SMA-PSI that may be disrupted during detergent isolation.
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Affiliation(s)
- Dmitry A Cherepanov
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Nathan G Brady
- Biochemistry and Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee
| | - Ivan V Shelaev
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Jon Nguyen
- Biochemistry and Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee
| | - Fedor E Gostev
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Mahir D Mamedov
- A. N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, Moscow, Russia
| | - Victor A Nadtochenko
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia.
| | - Barry D Bruce
- Biochemistry and Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee; Energy Science & Engineering Program, The Bredesen Center, University of Tennessee, Knoxville, Tennessee.
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14
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Zamzam N, Kaucikas M, Nürnberg DJ, Rutherford AW, van Thor JJ. Femtosecond infrared spectroscopy of chlorophyll f-containing photosystem I. Phys Chem Chem Phys 2019; 21:1224-1234. [DOI: 10.1039/c8cp05627g] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Femtosecond time resolved infrared spectroscopy of far-red light grown photosystem I shows chlorophyll f contributions in light harvesting and charge separation.
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Affiliation(s)
- Noura Zamzam
- Department of Life Sciences
- Imperial College London
- London
- UK
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15
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Shelaev IV, Mamedov MD, Gostev FE, Aybush AV, Li M, Nguyen J, Bruce BD, Nadtochenko VA. Comparisons of Electron Transfer Reactions in a Cyanobacterial Tetrameric and Trimeric Photosystem I Complexes. Photochem Photobiol 2018; 94:564-569. [DOI: 10.1111/php.12886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/05/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Ivan V. Shelaev
- N.N. Semenov Institute of Chemical Physics Russian Academy of Sciences Moscow Russia
| | - Mahir D. Mamedov
- A.N. Belozersky Institute of Physical–Chemical Biology Moscow State University Moscow Russia
| | - Fedor E. Gostev
- N.N. Semenov Institute of Chemical Physics Russian Academy of Sciences Moscow Russia
| | - Arseny V. Aybush
- N.N. Semenov Institute of Chemical Physics Russian Academy of Sciences Moscow Russia
| | - Meng Li
- Department of Biochemistry and Cellular and Molecular Biology University of Tennessee Knoxville TN
- Bredesen Center for Interdisciplinary Research University of Tennessee Knoxville TN
| | - Jonathan Nguyen
- Department of Biochemistry and Cellular and Molecular Biology University of Tennessee Knoxville TN
| | - Barry D. Bruce
- Department of Biochemistry and Cellular and Molecular Biology University of Tennessee Knoxville TN
- Bredesen Center for Interdisciplinary Research University of Tennessee Knoxville TN
- Department of Microbiology University of Tennessee Knoxville TN
| | - Victor A. Nadtochenko
- N.N. Semenov Institute of Chemical Physics Russian Academy of Sciences Moscow Russia
- Moscow Institute of Physics and Technology Dolgoprudny Russia
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16
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Oliver TAA. Recent advances in multidimensional ultrafast spectroscopy. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171425. [PMID: 29410844 PMCID: PMC5792921 DOI: 10.1098/rsos.171425] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/20/2017] [Indexed: 05/14/2023]
Abstract
Multidimensional ultrafast spectroscopies are one of the premier tools to investigate condensed phase dynamics of biological, chemical and functional nanomaterial systems. As they reach maturity, the variety of frequency domains that can be explored has vastly increased, with experimental techniques capable of correlating excitation and emission frequencies from the terahertz through to the ultraviolet. Some of the most recent innovations also include extreme cross-peak spectroscopies that directly correlate the dynamics of electronic and vibrational states. This review article summarizes the key technological advances that have permitted these recent advances, and the insights gained from new multidimensional spectroscopic probes.
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Affiliation(s)
- Thomas A. A. Oliver
- School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, UK
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17
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Mutations in algal and cyanobacterial Photosystem I that independently affect the yield of initial charge separation in the two electron transfer cofactor branches. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:42-55. [DOI: 10.1016/j.bbabio.2017.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 10/16/2017] [Accepted: 10/17/2017] [Indexed: 01/02/2023]
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18
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Mechanism of adiabatic primary electron transfer in photosystem I: Femtosecond spectroscopy upon excitation of reaction center in the far-red edge of the QY band. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:895-905. [DOI: 10.1016/j.bbabio.2017.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 11/23/2022]
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19
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Kaucikas M, Nürnberg D, Dorlhiac G, Rutherford AW, van Thor JJ. Femtosecond Visible Transient Absorption Spectroscopy of Chlorophyll f-Containing Photosystem I. Biophys J 2017; 112:234-249. [PMID: 28122212 PMCID: PMC5266252 DOI: 10.1016/j.bpj.2016.12.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/02/2016] [Accepted: 12/01/2016] [Indexed: 01/09/2023] Open
Abstract
Photosystem I (PSI) from Chroococcidiopsis thermalis PCC 7203 grown under far-red light (FRL; >725 nm) contains both chlorophyll a and a small proportion of chlorophyll f. Here, we investigated excitation energy transfer and charge separation using this FRL-grown form of PSI (FRL-PSI). We compared femtosecond transient visible absorption changes of normal, white-light (WL)-grown PSI (WL-PSI) with those of FRL-PSI using excitation at 670 nm, 700 nm, and (in the case of FRL-PSI) 740 nm. The possibility that chlorophyll f participates in energy transfer or charge separation is discussed on the basis of spectral assignments. With selective pumping of chlorophyll f at 740 nm, we observe a final ∼150 ps decay assigned to trapping by charge separation, and the amplitude of the resulting P700+•A1-• charge-separated state indicates that the yield is directly comparable to that of WL-PSI. The kinetics shows a rapid 2 ps time constant for almost complete transfer to chlorophyll f if chlorophyll a is pumped with a wavelength of 670 nm or 700 nm. Although the physical role of chlorophyll f is best supported as a low-energy radiative trap, the physical location should be close to or potentially within the charge-separating pigments to allow efficient transfer for charge separation on the 150 ps timescale. Target models can be developed that include a branching in the formation of the charge separation for either WL-PSI or FRL-PSI.
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Affiliation(s)
- Marius Kaucikas
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Dennis Nürnberg
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Gabriel Dorlhiac
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Jasper J. van Thor
- Department of Life Sciences, Imperial College London, London, United Kingdom,Corresponding author
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20
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Dylla NP, Faries KM, Wyllie RM, Swenson AM, Hanson DK, Holten D, Kirmaier C, Laible PD. Species differences in unlocking B‐side electron transfer in bacterial reaction centers. FEBS Lett 2016; 590:2515-26. [DOI: 10.1002/1873-3468.12264] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/13/2016] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - Ryan M. Wyllie
- Biosciences Division Argonne National Laboratory Lemont IL USA
| | | | | | - Dewey Holten
- Department of Chemistry Washington University St. Louis MO USA
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21
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Suomivuori CM, Winter NOC, Hättig C, Sundholm D, Kaila VRI. Exploring the Light-Capturing Properties of Photosynthetic Chlorophyll Clusters Using Large-Scale Correlated Calculations. J Chem Theory Comput 2016; 12:2644-51. [DOI: 10.1021/acs.jctc.6b00237] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Carl-Mikael Suomivuori
- Department
of Chemistry, University of Helsinki, P.O. Box 55 (A. I. Virtanens plats
1), FIN-00014 Helsinki, Finland
- Department
Chemie, Technische Universität München, Lichtenbergstraße 4, Garching, Germany
| | - Nina O. C. Winter
- Ruhr-University at Bochum, Universitätsstraße
150, 44801 Bochum, Germany
| | - Christof Hättig
- Ruhr-University at Bochum, Universitätsstraße
150, 44801 Bochum, Germany
| | - Dage Sundholm
- Department
of Chemistry, University of Helsinki, P.O. Box 55 (A. I. Virtanens plats
1), FIN-00014 Helsinki, Finland
| | - Ville R. I. Kaila
- Department
Chemie, Technische Universität München, Lichtenbergstraße 4, Garching, Germany
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22
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Lewis NHC, Dong H, Oliver TAA, Fleming GR. A method for the direct measurement of electronic site populations in a molecular aggregate using two-dimensional electronic-vibrational spectroscopy. J Chem Phys 2015; 143:124203. [DOI: 10.1063/1.4931634] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Nicholas H. C. Lewis
- Department of Chemistry, University of California, Berkeley, California 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; and Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, USA
| | - Hui Dong
- Department of Chemistry, University of California, Berkeley, California 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; and Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, USA
| | - Thomas A. A. Oliver
- Department of Chemistry, University of California, Berkeley, California 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; and Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, USA
| | - Graham R. Fleming
- Department of Chemistry, University of California, Berkeley, California 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; and Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, USA
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23
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Mamedov M, Nadtochenko V, Semenov A. Primary electron transfer processes in photosynthetic reaction centers from oxygenic organisms. PHOTOSYNTHESIS RESEARCH 2015; 125:51-63. [PMID: 25648636 DOI: 10.1007/s11120-015-0088-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/12/2015] [Indexed: 05/22/2023]
Abstract
This minireview is written in honor of Vladimir A. Shuvalov, a pioneer in the area of primary photochemistry of both oxygenic and anoxygenic photosyntheses (See a News Report: Allakhverdiev et al. 2014). In the present paper, we describe the current state of the formation of the primary and secondary ion-radical pairs within photosystems (PS) II and I in oxygenic organisms. Spectral-kinetic studies of primary events in PS II and PS I, upon excitation by ~20 fs laser pulses, are now available and reviewed here; for PS II, excitation was centered at 710 nm, and for PS I, it was at 720 nm. In PS I, conditions were chosen to maximally increase the relative contribution of the direct excitation of the reaction center (RC) in order to separate the kinetics of the primary steps of charge separation in the RC from that of the excitation energy transfer in the antenna. Our results suggest that the sequence of the primary electron transfer reactions is P680 → ChlD1 → PheD1 → QA (PS II) and P700 → A 0A/A 0B → A 1A/A 1B (PS I). However, alternate routes of charge separation in PS II, under different excitation conditions, are not ruled out.
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Affiliation(s)
- Mahir Mamedov
- A.N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, 119991, Moscow, Russia,
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24
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Tongra T, Jajoo A. Investigating changes in the redox state of Photosystem I at low pH. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 151:25-30. [PMID: 26151897 DOI: 10.1016/j.jphotobiol.2015.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 11/29/2022]
Abstract
Changes in the redox state of Photosystem I (PSI) were studied in spinach leaf discs suspended in buffers of different pH (pH 7.5, 6.5, 5.5 and 4.5). By measuring absorbance changes at 820 nm, it was observed that under normal conditions, the electrons were supplied by Photosystem II (PSII) for the photo-oxidation of P700 while in the presence of DCMU when electrons coming from PSII are blocked, cyclic electron flow (CEF) around PSI was the major source for the absorbance changes observed at 820 nm. This was supported by complete inhibition in the reduction of both single turnover (ST) area and multiple turnover (MT) area, in the presence of DCMU, which is generally filled up by the electrons coming from PSII. In the absence of DCMU, the intersystem electron pool or plastoquinone (PQ) pool was increased at low pH which was probably due to enhanced cyclic electron flow around PSI. Our results also suggest that at low pH, in the absence of DCMU, the major contribution for faster dark re-reduction of P700(+) is attributed mainly by PSII and CEF PSI while in the presence of DCMU, the significant contribution is provided by CEF PSI and other stromal components.
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Affiliation(s)
- Teena Tongra
- School of Life Science, Devi Ahilya University, Indore 452017, M.P., India
| | - Anjana Jajoo
- School of Life Science, Devi Ahilya University, Indore 452017, M.P., India.
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Nakashima S, Ogura T, Kitagawa T. Infrared and Raman spectroscopic investigation of the reaction mechanism of cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:86-97. [PMID: 25135480 DOI: 10.1016/j.bbabio.2014.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/07/2014] [Accepted: 08/11/2014] [Indexed: 10/24/2022]
Abstract
Recent progress in studies on the proton-pumping and O₂reduction mechanisms of cytochrome c oxidase (CcO) elucidated by infrared (IR) and resonance Raman (rR) spectroscopy, is reviewed. CcO is the terminal enzyme of the respiratory chain and its O₂reduction reaction is coupled with H⁺ pumping activity across the inner mitochondrial membrane. The former is catalyzed by heme a3 and its mechanism has been determined using a rR technique, while the latter used the protein moiety and has been investigated with an IR technique. The number of H⁺ relative to e⁻ transferred in the reaction is 1:1, and their coupling is presumably performed by heme a and nearby residues. To perform this function, different parts of the protein need to cooperate with each other spontaneously and sequentially. It is the purpose of this article to describe the structural details on the coupling on the basis of the vibrational spectra of certain specified residues and chromophores involved in the reaction. Recent developments in time-resolved IR and Raman technology concomitant with protein manipulation methods have yielded profound insights into such structural changes. In particular, the new IR techniques that yielded the breakthrough are reviewed and assessed in detail. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Satoru Nakashima
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Takashi Ogura
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan; Department of Life Science, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Teizo Kitagawa
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
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Hastings G. Vibrational spectroscopy of photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:55-68. [PMID: 25086273 DOI: 10.1016/j.bbabio.2014.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/01/2014] [Accepted: 07/21/2014] [Indexed: 11/28/2022]
Abstract
Fourier transform infrared difference spectroscopy (FTIR DS) has been widely used to study the structural details of electron transfer cofactors (and their binding sites) in many types of photosynthetic protein complexes. This review focuses in particular on work that has been done to investigate the A₁cofactor in photosystem I photosynthetic reaction centers. A review of this subject area last appeared in 2006 [1], so only work undertaken since then will be covered here. Following light excitation of intact photosystem I particles the P700⁺A⁻(1) secondary radical pair state is formed within 100ps. This state decays within 300ns at room temperature, or 300μs at 77K. Given the short-lived nature of this state, it is not easily studied using "static" photo-accumulation FTIR difference techniques at either temperature. Time-resolved techniques are required. This article focuses on the use of time-resolved step-scan FTIR DS for the study of the P700⁺A⁻(1) state in intact photosystem I. Up until now, only our group has undertaken studies in this area. So, in this article, recent work undertaken in our lab is described, where we have used low-temperature (77K), microsecond time-resolved step-scan FTIR DS to study the P700⁺A⁻(1) state in photosystem I. In photosystem I a phylloquinone molecule occupies the A₁binding site. However, different quinones can be incorporated into the A1 binding site, and here work is described for photosystem I particles with plastoquinone-9, 2-phytyl naphthoquinone and 2-methyl naphthoquinone incorporated into the A₁binding site. Studies in which ¹⁸O isotope labeled phylloquinone has been incorporated into the A1 binding site are also discussed. To fully characterize PSI particles with different quinones incorporated into the A1 binding site nanosecond to millisecond visible absorption spectroscopy has been shown to be of considerable value, especially so when undertaken using identical samples under identical conditions to that used in time-resolved step-scan FTIR measurements. In this article the latest work that has been undertaken using both visible and infrared time resolved spectroscopies on the same sample will be described. Finally, vibrational spectroscopic data that has been obtained for phylloquinone in the A1 binding site in photosystem I is compared to corresponding data for ubiquinone in the QA binding site in purple bacterial reaction centers. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Gary Hastings
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
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Ultrafast infrared spectroscopy in photosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:2-11. [PMID: 24973600 DOI: 10.1016/j.bbabio.2014.06.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 11/22/2022]
Abstract
In recent years visible pump/mid-infrared (IR) probe spectroscopy has established itself as a key technology to unravel structure-function relationships underlying the photo-dynamics of complex molecular systems. In this contribution we review the most important applications of mid-infrared absorption difference spectroscopy with sub-picosecond time-resolution to photosynthetic complexes. Considering several examples, such as energy transfer in photosynthetic antennas and electron transfer in reaction centers and even more intact structures, we show that the acquisition of ultrafast time resolved mid-IR spectra has led to new insights into the photo-dynamics of the considered systems and allows establishing a direct link between dynamics and structure, further strengthened by the possibility of investigating the protein response signal to the energy or electron transfer processes. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Savitsky A, Niklas J, Golbeck JH, Möbius K, Lubitz W. Orientation Resolving Dipolar High-Field EPR Spectroscopy on Disordered Solids: II. Structure of Spin-Correlated Radical Pairs in Photosystem I. J Phys Chem B 2013; 117:11184-99. [DOI: 10.1021/jp401573z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- A. Savitsky
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470
Mülheim an der Ruhr, Germany
| | - J. Niklas
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470
Mülheim an der Ruhr, Germany
| | - J. H. Golbeck
- Department of Biochemistry
and
Molecular Biology, Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802,
United States
| | - K. Möbius
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470
Mülheim an der Ruhr, Germany
- Department of Physics, Free University Berlin, Arnimallee 14, D-14195 Berlin,
Germany
| | - W. Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470
Mülheim an der Ruhr, Germany
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Zhu J, Mathes T, Stahl AD, Kennis JTM, Groot ML. Ultrafast mid-infrared spectroscopy by chirped pulse upconversion in 1800-1000cm(-1) region. OPTICS EXPRESS 2012; 20:10562-10571. [PMID: 22565682 DOI: 10.1364/oe.20.010562] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Broadband femtosecond mid-infrared pulses can be converted into the visible spectral region by chirped pulse upconversion. We report here the upconversion of pump probe transient signals in the frequency region below 1800cm(-1), using the nonlinear optical crystal AgGaGeS4, realizing an important expansion of the application range of this method. Experiments were demonstrated with a slab of GaAs, in which the upconverted signals cover a window of 120cm(-1), with 1.5cm(-1) resolution. In experiments on the BLUF photoreceptor Slr1694, signals below 1 milliOD were well resolved after baseline correction. Possibilities for further optimization of the method are discussed. We conclude that this method is an attractive alternative for the traditional MCT arrays used in most mid-infrared pump probe experiments.
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Affiliation(s)
- Jingyi Zhu
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands
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Wientjes E, Croce R. PMS: photosystem I electron donor or fluorescence quencher. PHOTOSYNTHESIS RESEARCH 2012; 111:185-91. [PMID: 21879310 PMCID: PMC3296009 DOI: 10.1007/s11120-011-9671-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/07/2011] [Indexed: 05/18/2023]
Abstract
Light energy harvested by the pigments in Photosystem I (PSI) is used for charge separation in the reaction center (RC), after which the positive charge resides on a special chlorophyll dimer called P700. In studies on the PSI trapping kinetics, P700(+) is usually chemically reduced to re-open the RCs. So far, the information available about the reduction rate and possible chlorophyll fluorescence quenching effects of these reducing agents is limited. This information is indispensible to estimate the fraction of open RCs under known experimental conditions. Moreover, it would be important to understand if these reagents have a chlorophyll fluorescence quenching effects to avoid the introduction of exogenous singlet excitation quenching in the measurements. In this study, we investigated the effect of the commonly used reducing agent phenazine methosulfate (PMS) on the RC and fluorescence emission of higher plant PSI-LHCI. We measured the P700(+) reduction rate for different PMS concentrations, and show that we can give a reliable estimation on the fraction of closed RCs based on these rates. The data show that PMS is quenching chlorophyll fluorescence emission. Finally, we determined that the fluorescence quantum yield of PSI with closed RCs is 4% higher than if the RCs are open.
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Affiliation(s)
- Emilie Wientjes
- Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
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Stahl AD, Crouch LI, Jones MR, van Stokkum I, van Grondelle R, Groot ML. Role of PufX in Photochemical Charge Separation in the RC-LH1 Complex from Rhodobacter sphaeroides: An Ultrafast Mid-IR Pump–Probe Investigation. J Phys Chem B 2011; 116:434-44. [DOI: 10.1021/jp206697k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Andreas D. Stahl
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Lucy I. Crouch
- School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Michael R. Jones
- School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Ivo van Stokkum
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Rienk van Grondelle
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Marie Louise Groot
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
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