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Cherepanov D, Aybush A, Johnson TW, Shelaev I, Gostev F, Mamedov M, Nadtochenko V, Semenov A. Inverted region in the reaction of the quinone reduction in the A 1-site of photosystem I from cyanobacteria. PHOTOSYNTHESIS RESEARCH 2024; 159:115-131. [PMID: 37093503 DOI: 10.1007/s11120-023-01020-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023]
Abstract
Photosystem I from the menB strain of Synechocystis sp. PCC 6803 containing foreign quinones in the A1 sites was used for studying the primary steps of electron transfer by pump-probe femtosecond laser spectroscopy. The free energy gap (- ΔG) of electron transfer between the reduced primary acceptor A0 and the quinones bound in the A1 site varied from 0.12 eV for the low-potential 1,2-diamino-anthraquinone to 0.88 eV for the high-potential 2,3-dichloro-1,4-naphthoquinone, compared to 0.5 eV for the native phylloquinone. It was shown that the kinetics of charge separation between the special pair chlorophyll P700 and the primary acceptor A0 was not affected by quinone substitutions, whereas the rate of A0 → A1 electron transfer was sensitive to the redox-potential of quinones: the decrease of - ΔG by 400 meV compared to the native phylloquinone resulted in a ~ fivefold slowing of the reaction The presence of the asymmetric inverted region in the ΔG dependence of the reaction rate indicates that the electron transfer in photosystem I is controlled by nuclear tunneling and should be treated in terms of quantum electron-phonon interactions. A three-mode implementation of the multiphonon model, which includes modes around 240 cm-1 (large-scale protein vibrations), 930 cm-1 (out-of-plane bending of macrocycles and protein backbone vibrations), and 1600 cm-1 (double bonds vibrations) was applied to rationalize the observed dependence. The modes with a frequency of at least 1600 cm-1 make the predominant contribution to the reorganization energy, while the contribution of the "classical" low-frequency modes is only 4%.
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Affiliation(s)
- Dmitry Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991.
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, bldg 40, Moscow, Russia, 119992.
| | - Arseny Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
| | - T Wade Johnson
- Department of Chemistry, Susquehanna University, 514 University Ave., Selinsgrove, PA, 17870, USA
| | - Ivan Shelaev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
| | - Fedor Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
| | - Mahir Mamedov
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, bldg 40, Moscow, Russia, 119992
| | - Victor Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
- Department of Chemistry, Lomonosov Moscow State University, Leninskiye Gory 1-3, Moscow, Russia, 119991
| | - Alexey Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991.
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, bldg 40, Moscow, Russia, 119992.
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Kondo T, Mutoh R, Arai S, kurisu G, Oh-oka H, Fujiyoshi S, Matsushita M. Energy transfer fluctuation observed by single-molecule spectroscopy of red-shifted bacteriochlorophyll in the homodimeric photosynthetic reaction center. J Chem Phys 2022; 156:105102. [DOI: 10.1063/5.0077290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Toru Kondo
- Department of Life Science and Technology, Tokyo Institute of Technology, Japan
| | | | - Shun Arai
- Tokyo Institute of Technology, Japan
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3
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EPR of Type I photosynthetic reaction centers. Methods Enzymol 2022; 666:413-450. [DOI: 10.1016/bs.mie.2022.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Biskup T. Structure-Function Relationship of Organic Semiconductors: Detailed Insights From Time-Resolved EPR Spectroscopy. Front Chem 2019; 7:10. [PMID: 30775359 PMCID: PMC6367236 DOI: 10.3389/fchem.2019.00010] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 01/07/2019] [Indexed: 11/22/2022] Open
Abstract
Organic photovoltaics (OPV) is a promising technology to account for the increasing demand for energy in form of electricity. Whereas the last decades have seen tremendous progress in the field witnessed by the steady increase in efficiency of OPV devices, we still lack proper understanding of fundamental aspects of light-energy conversion, demanding for systematic investigation on a fundamental level. A detailed understanding of the electronic structure of semiconducting polymers and their building blocks is essential to develop efficient materials for organic electronics. Illuminating conjugated polymers not only leads to excited states, but sheds light on some of the most important aspects of device efficiency in organic electronics as well. The interplay between electronic structure, morphology, flexibility, and local ordering, while at the heart of structure-function relationship of organic electronic materials, is still barely understood. (Time-resolved) electron paramagnetic resonance (EPR) spectroscopy is particularly suited to address these questions, allowing one to directly detect paramagnetic states and to reveal their spin-multiplicity, besides its clearly superior spectral resolution compared to optical methods. This article aims at giving a non-specialist audience an overview of what EPR spectroscopy and particularly its time-resolved variant (TREPR) can contribute to unraveling aspects of structure-function relationship in organic semiconductors.
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Affiliation(s)
- Till Biskup
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
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5
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Pérez AA, Ferlez BH, Applegate AM, Walters K, He Z, Shen G, Golbeck JH, Bryant DA. Presence of a [3Fe-4S] cluster in a PsaC variant as a functional component of the photosystem I electron transfer chain in Synechococcus sp. PCC 7002. PHOTOSYNTHESIS RESEARCH 2018; 136:31-48. [PMID: 28916964 DOI: 10.1007/s11120-017-0437-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
A site-directed C14G mutation was introduced into the stromal PsaC subunit of Synechococcus sp. strain PCC 7002 in vivo in order to introduce an exchangeable coordination site into the terminal FB [4Fe-4S] cluster of Photosystem I (PSI). Using an engineered PSI-less strain (psaAB deletion), psaC was deleted and replaced with recombinant versions controlled by a strong promoter, and the psaAB deletion was complemented. Modified PSI accumulated at lower levels in this strain and supported slower photoautotrophic growth than wild type. As-isolated PSI complexes containing PsaCC14G showed resonances with g values of 2.038 and 2.007 characteristic of a [3Fe-4S]1+ cluster. When the PSI complexes were illuminated at 15 K, these resonances partially disappeared and two new sets of resonances appeared. The majority set had g values of 2.05, 1.95, and 1.85, characteristic of FA-, and the minority set had g values of 2.11, 1.90, and 1.88 from FB' in the modified site. The S = 1/2 spin state of the latter implied the presence of a thiolate as the terminal ligand. The [3Fe-4S] clusters could be partially reconstituted with iron, producing a larger population of [4Fe-4S] clusters. Rates of flavodoxin reduction were identical in PSI complexes isolated from wild type and the PsaCC14G variant strain; this implied equivalent capacity for forward electron transfer in PSI complexes that contained [3Fe-4S] and [4Fe-4S] clusters. The development of this cyanobacterial strain is a first step toward translation of in vitro PSI-based biosolar molecular wire systems in vivo and provides new insights into the formation of Fe/S clusters.
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Affiliation(s)
- Adam A Pérez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, 40202, USA
| | - Bryan H Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 28824, USA
| | - Amanda M Applegate
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
- Musculoskeletal Transplant Foundation, Jessup, PA, 18434, USA
| | - Karim Walters
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Zhihui He
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA.
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Kondo T, Matsuoka M, Azai C, Kobayashi M, Itoh S, Oh-oka H. Light-Induced Electron Spin-Polarized (ESP) EPR Signal of the P800+ Menaquinone– Radical Pair State in Oriented Membranes of Heliobacterium modesticaldum: Role/Location of Menaquinone in the Homodimeric Type I Reaction Center. J Phys Chem B 2018; 122:2536-2543. [DOI: 10.1021/acs.jpcb.7b12171] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Toru Kondo
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan
| | - Masahiro Matsuoka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Chihiro Azai
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Masami Kobayashi
- Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Shigeru Itoh
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan
| | - Hirozo Oh-oka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
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Kondo T, Itoh S, Matsuoka M, Azai C, Oh-oka H. Menaquinone as the Secondary Electron Acceptor in the Type I Homodimeric Photosynthetic Reaction Center of Heliobacterium modesticaldum. J Phys Chem B 2015; 119:8480-9. [PMID: 26075484 DOI: 10.1021/acs.jpcb.5b03723] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The type I photosynthetic reaction center (RC) of heliobacteria (hRC) is a homodimer containing cofactors almost analogous to those in the plant photosystem I (PS I). However, its three-dimensional structure is not yet clear. PS I uses phylloquinone (PhyQ) as a secondary electron acceptor (A1), while the available evidence has suggested that menaquinone (MQ) in hRC has no function as A1. The present study identified a new transient electron spin-polarized electron paramagnetic resonance (ESP-EPR) signal, arising from the radical pair of the oxidized electron donor and the reduced electron acceptor (P800(+)MQ(-)), in the hRC core complex and membranes from Heliobacterium modesticaldum. The ESP signal could be detected at 5-20 K upon flash excitation only after prereduction of the iron-sulfur center, F(X), and was selectively lost by extraction of MQ with diethyl ether. MQ was suggested to be located closer to F(X) than PhyQ in PS I based on the simulation of the unique A/E (A, absorption; E, emission) ESP pattern, the reduction/oxidation rates of MQ, and the power saturation property of the static MQ(-) signal. The result revealed the quinone usage as the secondary electron acceptor in hRC, as in the case of PS I.
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Affiliation(s)
| | | | - Masahiro Matsuoka
- §Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Chihiro Azai
- §Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Hirozo Oh-oka
- §Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
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8
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Saboe PO, Lubner CE, McCool NS, Vargas-Barbosa NM, Yan H, Chan S, Ferlez B, Bazan GC, Golbeck JH, Kumar M. Two-dimensional protein crystals for solar energy conversion. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:7064-9. [PMID: 25155990 DOI: 10.1002/adma.201402375] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/18/2014] [Indexed: 05/03/2023]
Abstract
Two-dimensional photosynthetic protein crystals provide a high density of aligned reaction centers. We reconstitute the robust light harvesting protein Photosystem I into a 2D crystal with lipids and integrate the crystals into a photo-electrochemical device. A 4-fold photocurrent enhancement is measured by incorporating conjugated oligoelectrolytes to form a supporting conductive bilayer in the device which produces a high photocurrent of ∼600 μA per mg PSI deposited.
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Affiliation(s)
- Patrick O Saboe
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
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9
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Jiménez-Alonso S, Guasch J, Estévez-Braun A, Ratera I, Veciana J, Ravelo AG. Electronic and Cytotoxic Properties of 2-Amino-naphtho[2,3-b]furan-4,9-diones. J Org Chem 2011; 76:1634-43. [DOI: 10.1021/jo102233j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sandra Jiménez-Alonso
- Instituto Universitario de Bio-Orgánica “Antonio González”, Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez, 38206 La Laguna, Tenerife, Spain
- Instituto Canario de Investigaciones del Cáncer (ICIC)
| | - Judith Guasch
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (CSIC), Universitat Autònoma de Barcelona and CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 08193 Bellaterra, Barcelona, Spain
| | - Ana Estévez-Braun
- Instituto Universitario de Bio-Orgánica “Antonio González”, Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez, 38206 La Laguna, Tenerife, Spain
- Instituto Canario de Investigaciones del Cáncer (ICIC)
| | - Imma Ratera
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (CSIC), Universitat Autònoma de Barcelona and CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 08193 Bellaterra, Barcelona, Spain
| | - Jaume Veciana
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (CSIC), Universitat Autònoma de Barcelona and CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 08193 Bellaterra, Barcelona, Spain
| | - Angel G. Ravelo
- Instituto Universitario de Bio-Orgánica “Antonio González”, Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez, 38206 La Laguna, Tenerife, Spain
- Instituto Canario de Investigaciones del Cáncer (ICIC)
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10
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Santabarbara S, Galuppini L, Casazza AP. Bidirectional electron transfer in the reaction centre of photosystem I. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2010; 52:735-749. [PMID: 20666929 DOI: 10.1111/j.1744-7909.2010.00977.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In the past decade light-induced electron transfer reactions in photosystem I have been the subject of intensive investigations that have led to the elucidation of some unique characteristics, the most striking of which is the existence of two parallel, functional, redox active cofactors chains. This process is generally referred to as bidirectional electron transfer. Here we present a review of the principal evidences that have led to the uncovering of bidirectionality in the reaction centre of photosystem I. A special focus is dedicated to the results obtained combining time-resolved spectroscopic techniques, either difference absorption or electron paramagnetic resonance, with molecular genetics, which allows, through modification of the binding of redox active cofactors with the reaction centre subunits, an effect on their physical-chemical properties.
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Independent initiation of primary electron transfer in the two branches of the photosystem I reaction center. Proc Natl Acad Sci U S A 2010; 107:4123-8. [PMID: 20142514 DOI: 10.1073/pnas.0905407107] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Photosystem I (PSI) is a large pigment-protein complex that unites a reaction center (RC) at the core with approximately 100 core antenna chlorophylls surrounding it. The RC is composed of two cofactor branches related by a pseudo-C2 symmetry axis. The ultimate electron donor, P(700) (a pair of chlorophylls), and the tertiary acceptor, F(X) (a Fe(4)S(4) cluster), are both located on this axis, while each of the two branches is made up of a pair of chlorophylls (ec2 and ec3) and a phylloquinone (PhQ). Based on the observed biphasic reduction of F(X), it has been suggested that both branches in PSI are competent for electron transfer (ET), but the nature and rate of the initial electron transfer steps have not been established. We report an ultrafast transient absorption study of Chlamydomonas reinhardtii mutants in which specific amino acids donating H-bonds to the 13(1)-keto oxygen of either ec3(A) (PsaA-Tyr696) or ec3(B) (PsaB-Tyr676) are converted to Phe, thus breaking the H-bond to a specific ec3 cofactor. We find that the rate of primary charge separation (CS) is lowered in both mutants, providing direct evidence that the primary ET event can be initiated independently in each branch. Furthermore, the data provide further support for the previously published model in which the initial CS event occurs within an ec2/ec3 pair, generating a primary ec2(+)ec3(-) radical pair, followed by rapid reduction by P(700) in the second ET step. A unique kinetic modeling approach allows estimation of the individual ET rates within the two cofactor branches.
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van der Est A. Transient EPR: using spin polarization in sequential radical pairs to study electron transfer in photosynthesis. PHOTOSYNTHESIS RESEARCH 2009; 102:335-347. [PMID: 19255871 DOI: 10.1007/s11120-009-9411-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 02/04/2009] [Indexed: 05/27/2023]
Abstract
The light induced electron transfer in photosynthesis generates a series of sequential spin polarized radical pairs, and transient electron paramagnetic resonance (TREPR) is ideally suited to study the lifetimes and physical and electronic structures of these radical pairs. In this article, the basic principles of TREPR are outlined with emphasis on the electron spin polarization (ESP) that develops during the electron transfer process. Examples of the analysis of TREPR data are given to illustrate the information that can be obtained. Recent applications of the technique to study the functionality of reaction centers, light-induced structural changes, and protein-cofactor interactions are reviewed.
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Affiliation(s)
- Art van der Est
- Department of Chemistry, Brock University, Saint Catharines, ON, Canada.
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Srinivasan N, Golbeck JH. Protein–cofactor interactions in bioenergetic complexes: The role of the A1A and A1B phylloquinones in Photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1057-88. [DOI: 10.1016/j.bbabio.2009.04.010] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 04/14/2009] [Accepted: 04/22/2009] [Indexed: 10/20/2022]
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Niklas J, Epel B, Antonkine ML, Sinnecker S, Pandelia ME, Lubitz W. Electronic Structure of the Quinone Radical Anion A1•− of Photosystem I Investigated by Advanced Pulse EPR and ENDOR Techniques. J Phys Chem B 2009; 113:10367-79. [DOI: 10.1021/jp901890z] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jens Niklas
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470 Mülheim/Ruhr, Germany, and Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Boris Epel
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470 Mülheim/Ruhr, Germany, and Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Mikhail L. Antonkine
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470 Mülheim/Ruhr, Germany, and Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Sebastian Sinnecker
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470 Mülheim/Ruhr, Germany, and Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Maria-Eirini Pandelia
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470 Mülheim/Ruhr, Germany, and Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Wolfgang Lubitz
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470 Mülheim/Ruhr, Germany, and Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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Tryptophan 13C nuclear-spin polarization generated by intraprotein electron transfer in a LOV2 domain of the blue-light receptor phototropin. Biochem Soc Trans 2009; 37:382-6. [PMID: 19290867 DOI: 10.1042/bst0370382] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
(13)C-NMR experiments were performed on photo-excited fully and partially (13)C-labelled LOV2 domains of the blue-light receptor phototropin. In the present paper, we report on nuclear-spin polarized tryptophan resonances that are generated by light-induced intraprotein electron transfer to the FMN cofactor. The spectra are discussed with respect to earlier data obtained from (13)C-NMR experiments on unlabelled LOV2 domains that have been reconstituted with FMN (13)C isotopologues.
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16
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Hui Y, Chng ELK, Chng CYL, Poh HL, Webster RD. Hydrogen-Bonding Interactions between Water and the One- and Two-Electron-Reduced Forms of Vitamin K1: Applying Quinone Electrochemistry To Determine the Moisture Content of Non-Aqueous Solvents. J Am Chem Soc 2009; 131:1523-34. [DOI: 10.1021/ja8080428] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yanlan Hui
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Elaine Lay Khim Chng
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Cheryl Yi Lin Chng
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Hwee Ling Poh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Richard D. Webster
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
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Abstract
Protein dynamics are likely to play important, regulatory roles in many aspects of photosynthetic electron transfer, but a detailed description of these coupled protein conformational changes has been unavailable. In oxygenic photosynthesis, photosystem I catalyzes the light-driven oxidation of plastocyanin or cytochrome c and the reduction of ferredoxin. A chlorophyll (chl) a/a' heterodimer, P(700), is the secondary electron donor, and the two P(700) chl, are designated P(A) and P(B). We used specific chl isotopic labeling and reaction-induced Fourier-transform infrared spectroscopy to assign chl keto vibrational bands to P(A) and P(B). In the cyanobacterium, Synechocystis sp. PCC 6803, the chl keto carbon was labeled from (13)C-labeled glutamate, and the chl keto oxygen was labeled from (18)O(2). These isotope-based assignments provide new information concerning the structure of P(A)(+), which is found to give rise to two chl keto vibrational bands, with frequencies at 1653 and 1687 cm(-1). In contrast, P(A) gives rise to one chl keto band at 1638 cm(-1). The observation of two P(A)(+) keto frequencies is consistent with a protein relaxation-induced distribution in P(A)(+) hydrogen bonding. These results suggest a light-induced conformational change in photosystem I, which may regulate the oxidation of soluble electron donors and other electron-transfer reactions. This study provides unique information concerning the role of protein dynamics in oxygenic photosynthesis.
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Miyamoto R, Mino H, Kondo T, Itoh S, Oh-oka H. An Electron Spin-Polarized Signal of the P800+A1(Q)− State in the Homodimeric Reaction Center Core Complex of Heliobacterium modesticaldum. Biochemistry 2008; 47:4386-93. [DOI: 10.1021/bi701612v] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryo Miyamoto
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan, and Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Hiroyuki Mino
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan, and Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Toru Kondo
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan, and Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Shigeru Itoh
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan, and Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Hirozo Oh-oka
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan, and Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
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19
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Ali K, Santabarbara S, Heathcote P, Evans MCW, Purton S. Bidirectional electron transfer in photosystem I: Replacement of the symmetry-breaking tryptophan close to the PsaB-bound phylloquinone (A1B) with a glycine residue alters the redox properties of A1B and blocks forward electron transfer at cryogenic temperatures. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1623-33. [PMID: 16989769 DOI: 10.1016/j.bbabio.2006.07.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 07/14/2006] [Accepted: 07/24/2006] [Indexed: 11/25/2022]
Abstract
A conserved tryptophan residue located between the A(1B) and F(X) redox centres on the PsaB side of the Photosystem I reaction centre has been mutated to a glycine in Chlamydomonas reinhardtii, thereby matching the conserved residue found in the equivalent position on the PsaA side. This mutant (PsaB:W669G) was studied using EPR spectroscopy with a view to understanding the molecular basis of the reported kinetic differences in forward electron transfer from the A(1A) and the A(1B) phyllo(semi)quinones. The kinetics of A(1)(-) reoxidation due to forward electron transfer or charge recombination were measured by electron spin echo spectroscopy at 265 K and 100 K, respectively. At 265 K, the reoxidation kinetics are considerably lengthened in the mutant in comparison to the wild-type. Under conditions in which F(X) is initially oxidised the kinetics of charge recombination at 100 K are found to be biphasic in the mutant while they are substantially monophasic in the wild-type. Pre-reduction of F(X) leads to biphasic kinetics in the wild-type, but does not alter the already biphasic kinetic properties of the PsaB:W669G mutant. Reduction of the [4Fe-4S] clusters F(A) and F(B) by illumination at 15 K is suppressed in the mutant. The results provide further support for the bi-directional model of electron transfer in Photosystem I of C. reinhardtii, and indicate that the replacement of the tryptophan residue with glycine mainly affects the redox properties of the PsaB bound phylloquinone A(1B).
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Affiliation(s)
- Kulsam Ali
- Department of Biology, University College London, Gower Street, London WC1E 6BT, UK
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20
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Kandrashkin Y, Asano MS, van der Est A. Observation of a photoexcited state of a paramagnetic transition metal complex by time-resolved electron paramagnetic resonance spectroscopy. Phys Chem Chem Phys 2006; 8:2129-32. [PMID: 16751870 DOI: 10.1039/b602529c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first observation of a spin polarized excited state of a paramagnetic metal-complex using time-resolved electron paramagnetic resonance (TREPR) spectroscopy is reported for octaethylporphinatooxovanadium(iv). The TREPR spectra show well resolved orientation dependent hyperfine splitting to the I = 7/2 vanadium nucleus. The reduction of the hyperfine splitting by a factor of 3 compared to the ground state and the observation of a multiplet pattern of spin polarization allow the TREPR spectra to be assigned to the excited quartet state of the complex. The spin polarization patterns evolve with time and it is postulated that this is a result of the equilibration between the lowest excited quartet and doublet states.
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Affiliation(s)
- Yuri Kandrashkin
- Department of Chemistry, Brock University, 500 Glenridge Ave., St. Catharines Ont., Canada L2S 3A1
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21
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Rappaport F, Diner BA, Redding K. Optical Measurements of Secondary Electron Transfer in Photosystem I. PHOTOSYSTEM I 2006. [DOI: 10.1007/978-1-4020-4256-0_16] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Santabarbara S, Heathcote P, Evans MCW. Modelling of the electron transfer reactions in Photosystem I by electron tunnelling theory: The phylloquinones bound to the PsaA and the PsaB reaction centre subunits of PS I are almost isoenergetic to the iron–sulfur cluster FX. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1708:283-310. [PMID: 15975545 DOI: 10.1016/j.bbabio.2005.05.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 04/12/2005] [Accepted: 05/03/2005] [Indexed: 10/25/2022]
Abstract
Photosystem I is a large macromolecular complex located in the thylakoid membranes of chloroplasts and in cyanobacteria that catalyses the light driven reduction of ferredoxin and oxidation of plastocyanin. Due to the very negative redox potential of the primary electron transfer cofactors accepting electrons, direct estimation by redox titration of the energetics of the system is hampered. However, the rates of electron transfer reactions are related to the thermodynamic properties of the system. Hence, several spectroscopic and biochemical techniques have been employed, in combination with the classical Marcus theory for electron transfer tunnelling, in order to access these parameters. Nevertheless, the values which have been presented are very variable. In particular, for the case of the tightly bound phylloquinone molecule A(1), the values of the redox potentials reported in the literature vary over a range of about 350 mV. Previous models of Photosystem I have assumed a unidirectional electron transfer model. In the present study, experimental evidence obtained by means of time resolved absorption, photovoltage, and electron paramagnetic resonance measurements are reviewed and analysed in terms of a bi-directional kinetic model for electron transfer reactions. This model takes into consideration the thermodynamic equilibrium between the iron-sulfur centre F(X) and the phylloquinone bound to either the PsaA (A(1A)) or the PsaB (A(1B)) subunit of the reaction centre and the equilibrium between the iron-sulfur centres F(A) and F(B). The experimentally determined decay lifetimes in the range of sub-picosecond to the microsecond time domains can be satisfactorily simulated, taking into consideration the edge-to-edge distances between redox cofactors and driving forces reported in the literature. The only exception to this general behaviour is the case of phylloquinone (A(1)) reoxidation. In order to describe the reported rates of the biphasic decay, of about 20 and 200 ns, associated with this electron transfer step, the redox potentials of the quinones are estimated to be almost isoenergetic with that of the iron sulfur centre F(X). A driving force in the range of 5 to 15 meV is estimated for these reactions, being slightly exergonic in the case of the A(1B) quinone and slightly endergonic, in the case of the A(1A) quinone. The simulation presented in this analysis not only describes the kinetic data obtained for the wild type samples at room temperature and is consistent with estimates of activation energy by the analysis of temperature dependence, but can also explain the effect of the mutations around the PsaB quinone binding pocket. A model of the overall energetics of the system is derived, which suggests that the only substantially irreversible electron transfer reactions are the reoxidation of A(0) on both electron transfer branches and the reduction of F(A) by F(X).
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Affiliation(s)
- Stefano Santabarbara
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
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23
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Sakuragi Y, Zybailov B, Shen G, Bryant DA, Golbeck JH, Diner BA, Karygina I, Pushkar Y, Stehlik D. Recruitment of a Foreign Quinone into the A1 Site of Photosystem I. J Biol Chem 2005; 280:12371-81. [PMID: 15681848 DOI: 10.1074/jbc.m412943200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A photosystem I (PS I) complex containing plastoquinone-9 (PQ-9) but devoid of F(X), F(B), and F(A) was isolated and characterized from a mutant strain of Synechococcus sp. PCC 7002 in which the menB and rubA genes were insertionally inactivated. In isolated PS I trimers, the decay of P700+ measured in the near-IR and the decay of A1- measured in the near-UV were found to be biphasic, with (averaged) room temperature lifetimes of 12 and 350 micros. The decay-associated spectra of both kinetic phases are characteristic of the oxidized minus reduced difference spectrum of a semiquinone, consistent with charge recombination between P700+ and PQ-9-. The amplitude of the flash-induced absorbance changes in both the near-IR and the near-UV show that approximately one-half of the A1 binding sites are either empty or nonfunctional. A spin-polarized chlorophyll triplet is observed by time-resolved EPR, and it is attributed to the 3P700 product of P700+A0- charge recombination via the T0 spin level in those PS I complexes that do not contain a functional quinone. In those A1 sites that are occupied, the P700+Q- polarization pattern indicates that PQ-9 is oriented in a similar manner to that in the menB mutant. When excess 9,10-anthraquinone is added in vitro, it displaces PQ-9 and occupies the A1 binding site more readily than in the menB mutant. This can be explained by a greater accessibility to the A1 site in the menB rubA mutant due to the absence of F(X) and the stromal ridge polypeptides. The relatively low binding affinity of 9,10-anthraquinone allows it to be readily removed from the A1 site by washing. However, all A1 sites are shown to bind napthoquinones with high affinity and thus are proven to be functionally competent in quinone binding. The ability to readily displace PQ-9 from the A1 site makes the menB rubA mutant ideal for introducing novel quinones, particularly anthraquinones, into PS I.
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Affiliation(s)
- Yumiko Sakuragi
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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24
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Pushkar YN, Karyagina I, Stehlik D, Brown S, van der Est A. Recruitment of a Foreign Quinone into the A1 Site of Photosystem I. J Biol Chem 2005; 280:12382-90. [PMID: 15640524 DOI: 10.1074/jbc.m412940200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In photosystem I (PS I), phylloquinone (PhQ) acts as a low potential electron acceptor during light-induced electron transfer (ET). The origin of the very low midpoint potential of the quinone is investigated by introducing anthraquinone (AQ) into PS I in the presence and absence of the iron-sulfur clusters. Solvent extraction and reincubation is used to obtain PS I particles containing AQ and the iron-sulfur clusters, whereas incubation of the menB rubA double mutant yields PS I with AQ in the PhQ site but no iron-sulfur clusters. Transient electron paramagnetic resonance spectroscopy is used to investigate the orientation of AQ in the binding site and the ET kinetics. The low temperature spectra suggest that the orientation of AQ in all samples is the same as that of PhQ in native PS I. In PS I containing the iron sulfur clusters, (i) the rate of forward electron transfer from the AQ*- to F(X) is found to be faster than from PhQ*- to F(X), and (ii) the spin polarization patterns provide indirect evidence that the preceding ET step from A0*- to quinone is slower than in the native system. The changes in the kinetics are in accordance with the more negative reduction midpoint potential of AQ. Moreover, a comparison of the spectra in the presence and absence of the iron-sulfur clusters suggests that the midpoint potential of AQ is more negative in the presence of F(X). The electron transfer from the AQ- to F(X) is found to be thermally activated with a lower apparent activation energy than for PhQ in native PS I. The spin polarization patterns show that the triplet character in the initial state of P700)*+AQ*- increases with temperature. This behavior is rationalized in terms of a model involving a distribution of lifetimes/redox potentials for A0 and related competition between charge recombination and forward electron transfer from the radical pair P700*+A0*-.
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Affiliation(s)
- Yulia N Pushkar
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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25
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Heinen U, Poluektov O, Stavitski E, Berthold T, Ohmes E, Schlesselman SL, Golecki JR, Moro GJ, Levanon H, Thurnauer MC, Kothe G. Magnetic-Field-Induced Orientation of Photosynthetic Reaction Centers, As Revealed by Time-Resolved D-Band Electron Paramagnetic Resonance of Spin-Correlated Radical Pairs. II. Field Dependence of the Alignment. J Phys Chem B 2004. [DOI: 10.1021/jp036232c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Ulrich Heinen
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Oleg Poluektov
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Eli Stavitski
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Thomas Berthold
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Ernst Ohmes
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Sandra L. Schlesselman
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Jochen R. Golecki
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Giorgio J. Moro
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Haim Levanon
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Marion C. Thurnauer
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
| | - Gerd Kothe
- Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, D-79104, Freiburg/Germany, Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, Department of Microbiology, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg/Germany, and Department of Physical Chemistry, University of Padova, Via Loredan 2, I-35131 Padova, Italy
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26
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Xu W, Chitnis PR, Valieva A, van der Est A, Brettel K, Guergova-Kuras M, Pushkar YN, Zech SG, Stehlik D, Shen G, Zybailov B, Golbeck JH. Electron transfer in cyanobacterial photosystem I: II. Determination of forward electron transfer rates of site-directed mutants in a putative electron transfer pathway from A0 through A1 to FX. J Biol Chem 2003; 278:27876-87. [PMID: 12721306 DOI: 10.1074/jbc.m302965200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The directionality of electron transfer in Photosystem I (PS I) is investigated using site-directed mutations in the phylloquinone (QK) and FX binding regions of Synnechocystis sp. PCC 6803. The kinetics of forward electron transfer from the secondary acceptor A1 (phylloquinone) were measured in mutants using time-resolved optical difference spectroscopy and transient EPR spectroscopy. In whole cells and PS I complexes of the wild-type both techniques reveal a major, slow kinetic component of tau approximately 300 ns while optical data resolve an additional minor kinetic component of tau approximately 10 ns. Whole cells and PS I complexes from the W697FPsaA and S692CPsaA mutants show a significant slowing of the slow kinetic component, whereas the W677FPsaB and S672CPsaB mutants show a less significant slowing of the fast kinetic component. Transient EPR measurements at 260 K show that the slow phase is approximately 3 times slower than at room temperature. Simulations of the early time behavior of the spin polarization pattern of P700+A1-, in which the decay rate of the pattern is assumed to be negligibly small, reproduce the observed EPR spectra at 260 K during the first 100 ns following laser excitation. Thus any spin polarization from P700+FX- in this time window is very weak. From this it is concluded that the relative amplitude of the fast phase is negligible at 260 K or its rate is much less temperature-dependent than that of the slow component. Together, the results demonstrate that the slow kinetic phase results from electron transfer from QK-A to FX and that this accounts for at least 70% of the electrons. Although the assignment of the fast kinetic phase remains uncertain, it is not strongly temperature dependent and it represents a minor fraction of the electrons being transferred. All of the results point toward asymmetry in electron transfer, and indicate that forward transfer in cyanobacterial PS I is predominantly along the PsaA branch.
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Affiliation(s)
- Wu Xu
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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27
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Xu W, Chitnis P, Valieva A, van der Est A, Pushkar YN, Krzystyniak M, Teutloff C, Zech SG, Bittl R, Stehlik D, Zybailov B, Shen G, Golbeck JH. Electron transfer in cyanobacterial photosystem I: I. Physiological and spectroscopic characterization of site-directed mutants in a putative electron transfer pathway from A0 through A1 to FX. J Biol Chem 2003; 278:27864-75. [PMID: 12721305 DOI: 10.1074/jbc.m302962200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Photosystem I (PS I) reaction center contains two branches of nearly symmetric cofactors bound to the PsaA and PsaB heterodimer. From the x-ray crystal structure it is known that Trp697PsaA and Trp677PsaB are pi-stacked with the head group of the phylloquinones and are H-bonded to Ser692PsaA and Ser672PsaB, whereas Arg694PsaA and Arg674PsaB are involved in a H-bonded network of side groups that connects the binding environments of the phylloquinones and FX. The mutants W697FPsaA, W677FPsaB, S692CPsaA, S672CPsaB, R694APsaA, and R674APsaB were constructed and characterized. All mutants grew photoautotrophically, yet all showed diminished growth rates compared with the wild-type, especially at higher light intensities. EPR and electron nuclear double resonance (ENDOR) studies at both room temperature and in frozen solution showed that the PsaB mutants were virtually identical to the wild-type, whereas significant effects were observed in the PsaA mutants. Spin polarized transient EPR spectra of the P700+A1- radical pair show that none of the mutations causes a significant change in the orientation of the measured phylloquinone. Pulsed ENDOR spectra reveal that the W697FPsaA mutation leads to about a 5% increase in the hyperfine coupling of the methyl group on the phylloquinone ring, whereas the S692CPsaA mutation causes a similar decrease in this coupling. The changes in the methyl hyperfine coupling are also reflected in the transient EPR spectra of P700+A1- and the CW EPR spectra of photoaccumulated A1-. We conclude that: (i) the transient EPR spectra at room temperature are predominantly from radical pairs in the PsaA branch of cofactors; (ii) at low temperature the electron cycle involving P700 and A1 similarly occurs along the PsaA branch of cofactors; and (iii) mutation of amino acids in close contact with the PsaA side quinone leads to changes in the spin density distribution of the reduced quinone observed by EPR.
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Affiliation(s)
- Wu Xu
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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28
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Fuhs M, Schnegg A, Prisner T, Köhne I, Hanley J, Rutherford A, Möbius K. Orientation selection in photosynthetic PS I multilayers: structural investigation of the charge separated state P(700)(+z.rad;)A(1)(-z.rad;) by high-field/high-frequency time-resolved EPR at 3.4 T/95 GHz. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1556:81-8. [PMID: 12351221 DOI: 10.1016/s0005-2728(02)00338-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The radical-pair state of the primary electron donor and the secondary electron acceptor (P(700)(+z.rad;)A(1)(-z.rad;)) of the photosynthetic reaction center (RC) photosystem I (PS I) of Synechocystis PCC 6803 was studied by time-resolved electron paramagnetic resonance (TREPR) at high field/high frequency (3.4 T/95 GHz) using orientation selection in multilayers. The goal of the present article is to work out the basis for future studies, in which the improved resolution of such multilayers may be used to detect mutation-induced structural changes of PS I in membrane preparations. This approach is particularly interesting for systems that cannot be prepared as single crystals. However, in order to use such multilayers for structural investigations of protein complexes, it is necessary to know their orientation distribution. PS I was chosen as a test example because the wild type was recently crystallized and its X-ray structure determined to 2.5 A resolution [Nature 411 (2001) 909]. On the basis of our experimental results we determined the orientation distribution. Furthermore, a simulation model for the general case in which the orientation distribution is not axially symmetric about the C(2) symmetry axis of the RC is developed and discussed. Spectra simulations show that changes in the TREPR spectra of PS I are much more significant for these oriented multilayers than for disordered samples. In this way the use of oriented multilayers, in conjunction with multifrequency TREPR measurements on oriented as well as on disordered samples, is a promising approach for studies of structural changes of PS I systems that are induced by point mutations.
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Affiliation(s)
- M Fuhs
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195, Berlin, Germany.
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29
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Fursman CE, Teutloff C, Bittl R. Pulsed ENDOR Studies of Short-Lived Spin-Correlated Radical Pairs in Photosynthetic Reaction Centers. J Phys Chem B 2002. [DOI: 10.1021/jp0257202] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Catherine E. Fursman
- Max-Volmer-Laboratorium, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Christian Teutloff
- Max-Volmer-Laboratorium, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Robert Bittl
- Max-Volmer-Laboratorium, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
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30
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Spin relaxation of a spin-correlated radical pair P700+A1− in the PSI photosynthetic reaction center. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)01083-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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31
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KANDRASHKIN YUE, VOLLMANN W, STEHLIK D, SALIKHOV K, VAN DER EST A. The magnetic field dependence of the electron spin polarization in consecutive spin correlated radical pairs in type I photosynthetic reaction centres. Mol Phys 2002. [DOI: 10.1080/00268970110118240] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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32
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Bittl R, Zech SG. Pulsed EPR spectroscopy on short-lived intermediates in Photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1507:194-211. [PMID: 11687215 DOI: 10.1016/s0005-2728(01)00210-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The application of pulsed electron paramagnetic resonance spectroscopy on short-lived intermediates in Photosystem I is reviewed. The spin polarization in light-induced radical pairs gives rise to a phase shifted 'out-of-phase' electron spin echo signal. This echo signal shows a prominent modulation of its intensity as a function of the spacing between the two microwave pulses. Its modulation frequency is determined by the electron-electron spin couplings within the radical pair. Thereby, the measurement of the dipolar coupling gives direct information about the spin-spin distance and can therefore be used to determine cofactor distances with high precision. Application of this technique to the radical pair P(*+)(700)A(*-)(1) in Photosystem I is discussed. Moreover, if oriented samples (e.g. single crystals) are used, the angular dependence of the dipolar coupling can be used to derive the orientation of the axis connecting donor and acceptor with respect to an external (crystal) axes system. Using out-of-phase electron spin echo envelope modulation spectroscopy, the localization of the secondary acceptor quinone A(1) has become possible.
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Affiliation(s)
- R Bittl
- Max-Volmer-Institut, Technische Universität Berlin, Germany.
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Abstract
This mini-review focuses on recent experimental results and questions, which came up since the last more comprehensive reviews on the subject. We include a brief discussion of the different techniques used for time-resolved studies of electron transfer in photosystem I (PS I) and relate the kinetic results to new structural data of the PS I reaction centre.
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Affiliation(s)
- K Brettel
- Section de Bioénergétique and CNRS URA 2096, Département de Biologie Cellulaire et Moléculaire, CEA Saclay, 91191 Cedex, Gif-sur-Yvette, France.
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