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Gu X, Li L, Li S, Shi W, Zhong X, Su Y, Wang T. Adaptive evolution and co-evolution of chloroplast genomes in Pteridaceae species occupying different habitats: overlapping residues are always highly mutated. BMC PLANT BIOLOGY 2023; 23:511. [PMID: 37880608 PMCID: PMC10598918 DOI: 10.1186/s12870-023-04523-1] [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: 07/11/2023] [Accepted: 10/13/2023] [Indexed: 10/27/2023]
Abstract
BACKGROUND The evolution of protein residues depends on the mutation rates of their encoding nucleotides, but it may also be affected by co-evolution with other residues. Chloroplasts function as environmental sensors, transforming fluctuating environmental signals into different physiological responses. We reasoned that habitat diversity may affect their rate and mode of evolution, which might be evidenced in the chloroplast genome. The Pteridaceae family of ferns occupy an unusually broad range of ecological niches, which provides an ideal system for analysis. RESULTS We conducted adaptive evolution and intra-molecular co-evolution analyses of Pteridaceae chloroplast DNAs (cpDNAs). The results indicate that the residues undergoing adaptive evolution and co-evolution were mostly independent, with only a few residues being simultaneously involved in both processes, and these overlapping residues tend to exhibit high mutations. Additionally, our data showed that Pteridaceae chloroplast genes are under purifying selection. Regardless of whether we grouped species by lineage (which corresponded with ecological niches), we determined that positively selected residues mainly target photosynthetic genes. CONCLUSIONS Our work provides evidence for the adaptive evolution of Pteridaceae cpDNAs, especially photosynthetic genes, to different habitats and sheds light on the adaptive evolution and co-evolution of proteins.
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Affiliation(s)
- Xiaolin Gu
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Lingling Li
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Sicong Li
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Wanxin Shi
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Xiaona Zhong
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yingjuan Su
- School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China.
- Research Institute of Sun Yat-sen University in Shenzhen, Shenzhen, 518057, China.
| | - Ting Wang
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
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López-Ortiz M, Zamora RA, Giannotti MI, Gorostiza P. The Protein Matrix of Plastocyanin Supports Long-Distance Charge Transport with Photosystem I and the Copper Ion Regulates Its Spatial Span and Conductance. ACS NANO 2023; 17:20334-20344. [PMID: 37797170 DOI: 10.1021/acsnano.3c06390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Charge exchange is the fundamental process that sustains cellular respiration and photosynthesis by shuttling electrons in a cascade of electron transfer (ET) steps between redox cofactors. While intraprotein charge exchange is well characterized in protein complexes bearing multiple redox sites, interprotein processes are less understood due to the lack of suitable experimental approaches and the dynamic nature of the interactions. Proteins constrained between electrodes are known to support electron transport (ETp) through the protein matrix even without redox cofactors, as the charges housed by the redox sites in ET are furnished by the electrodes. However, it is unknown whether protein ETp mechanisms apply to the interprotein medium present under physiological conditions. We study interprotein charge exchange between plant photosystem I (PSI) and its soluble redox partner plastocyanin (Pc) and address the role of the Pc copper center. Using electrochemical scanning tunneling spectroscopy (ECSTS) current-distance and blinking measurements, we quantify the spatial span of charge exchange between individual Pc/PSI pairs and ETp through transient Pc/PSI complexes. Pc devoid of the redox center (Pcapo) can exchange charge with PSI at longer distances than with the copper ion (Pcholo). Conductance bursts associated with Pcapo/PSI complex formation are higher than in Pcholo/PSI. Thus, copper ions are not required for long-distance Pc/PSI ETp but regulate its spatial span and conductance. Our results suggest that the redox center that carries the charge in Pc is not necessary to exchange it in interprotein ET through the aqueous solution and question the canonical view of tight complex binding between redox protein partners.
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Affiliation(s)
- Manuel López-Ortiz
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
| | - Ricardo A Zamora
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
| | - Marina I Giannotti
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
- Department of Materials Science and Physical Chemistry, University of Barcelona, Martí i Franquès 1-11, Barcelona 08028, Spain
| | - Pau Gorostiza
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona 08010, Spain
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3
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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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Zamora RA, López-Ortiz M, Sales-Mateo M, Hu C, Croce R, Maniyara RA, Pruneri V, Giannotti MI, Gorostiza P. Light- and Redox-Dependent Force Spectroscopy Reveals that the Interaction between Plastocyanin and Plant Photosystem I Is Favored when One Partner Is Ready for Electron Transfer. ACS NANO 2022; 16:15155-15164. [PMID: 36067071 DOI: 10.1021/acsnano.2c06454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Photosynthesis is a fundamental process that converts photons into chemical energy, driven by large protein complexes at the thylakoid membranes of plants, cyanobacteria, and algae. In plants, water-soluble plastocyanin (Pc) is responsible for shuttling electrons between cytochrome b6f complex and the photosystem I (PSI) complex in the photosynthetic electron transport chain (PETC). For an efficient turnover, a transient complex must form between PSI and Pc in the PETC, which implies a balance between specificity and binding strength. Here, we studied the binding frequency and the unbinding force between suitably oriented plant PSI and Pc under redox control using single molecule force spectroscopy (SMFS). The binding frequency (observation of binding-unbinding events) between PSI and Pc depends on their respective redox states. The interaction between PSI and Pc is independent of the redox state of PSI when Pc is reduced, and it is disfavored in the dark (reduced P700) when Pc is oxidized. The frequency of interaction between PSI and Pc is higher when at least one of the partners is in a redox state ready for electron transfer (ET), and the post-ET situation (PSIRed-PcOx) leads to lower binding. In addition, we show that the binding of ET-ready PcRed to PSI can be regulated externally by Mg2+ ions in solution.
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Affiliation(s)
- Ricardo A Zamora
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
| | - Manuel López-Ortiz
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
| | - Montserrat Sales-Mateo
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Chen Hu
- Biophysics of Photosynthesis. Dep. Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Roberta Croce
- Biophysics of Photosynthesis. Dep. Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Rinu Abraham Maniyara
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels 08860, Spain
| | - Valerio Pruneri
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels 08860, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona 08010, Spain
| | - Marina I Giannotti
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
- Department of Materials Science and Physical Chemistry, University of Barcelona, Martí i Franquès 10, Barcelona 08028, Spain
| | - Pau Gorostiza
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona 08010, Spain
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5
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López-Ortiz M, Zamora RA, Giannotti MI, Hu C, Croce R, Gorostiza P. Distance and Potential Dependence of Charge Transport Through the Reaction Center of Individual Photosynthetic Complexes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2104366. [PMID: 34874621 DOI: 10.1002/smll.202104366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/11/2021] [Indexed: 06/13/2023]
Abstract
Charge separation and transport through the reaction center of photosystem I (PSI) is an essential part of the photosynthetic electron transport chain. A strategy is developed to immobilize and orient PSI complexes on gold electrodes allowing to probe the complex's electron acceptor side, the chlorophyll special pair P700. Electrochemical scanning tunneling microscopy (ECSTM) imaging and current-distance spectroscopy of single protein complex shows lateral size in agreement with its known dimensions, and a PSI apparent height that depends on the probe potential revealing a gating effect in protein conductance. In current-distance spectroscopy, it is observed that the distance-decay constant of the current between PSI and the ECSTM probe depends on the sample and probe electrode potentials. The longest charge exchange distance (lowest distance-decay constant β) is observed at sample potential 0 mV/SSC (SSC: reference electrode silver/silver chloride) and probe potential 400 mV/SSC. These potentials correspond to hole injection into an electronic state that is available in the absence of illumination. It is proposed that a pair of tryptophan residues located at the interface between P700 and the solution and known to support the hydrophobic recognition of the PSI redox partner plastocyanin, may have an additional role as hole exchange mediator in charge transport through PSI.
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Affiliation(s)
- Manuel López-Ortiz
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona, 08028, Spain
- Network Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, 28029, Spain
| | - Ricardo A Zamora
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona, 08028, Spain
- Network Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, 28029, Spain
| | - Marina Inés Giannotti
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona, 08028, Spain
- Network Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, 28029, Spain
- Department of Materials Science and Physical Chemistry, University of Barcelona, Martí i Franquès 1-11, Barcelona, 08028, Spain
| | - Chen Hu
- Biophysics of PhotosynthesisDepartment of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam, 1081 HV, The Netherlands
| | - Roberta Croce
- Biophysics of PhotosynthesisDepartment of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, Amsterdam, 1081 HV, The Netherlands
| | - Pau Gorostiza
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona, 08028, Spain
- Network Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, 28029, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, 08010, Spain
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6
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Castell C, Rodríguez-Lumbreras LA, Hervás M, Fernández-Recio J, Navarro JA. New Insights into the Evolution of the Electron Transfer from Cytochrome f to Photosystem I in the Green and Red Branches of Photosynthetic Eukaryotes. PLANT & CELL PHYSIOLOGY 2021; 62:1082-1093. [PMID: 33772595 PMCID: PMC8557733 DOI: 10.1093/pcp/pcab044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/15/2021] [Indexed: 05/11/2023]
Abstract
In cyanobacteria and most green algae of the eukaryotic green lineage, the copper-protein plastocyanin (Pc) alternatively replaces the heme-protein cytochrome c6 (Cc6) as the soluble electron carrier from cytochrome f (Cf) to photosystem I (PSI). The functional and structural equivalence of 'green' Pc and Cc6 has been well established, representing an example of convergent evolution of two unrelated proteins. However, plants only produce Pc, despite having evolved from green algae. On the other hand, Cc6 is the only soluble donor available in most species of the red lineage of photosynthetic organisms, which includes, among others, red algae and diatoms. Interestingly, Pc genes have been identified in oceanic diatoms, probably acquired by horizontal gene transfer from green algae. However, the mechanisms that regulate the expression of a functional Pc in diatoms are still unclear. In the green eukaryotic lineage, the transfer of electrons from Cf to PSI has been characterized in depth. The conclusion is that in the green lineage, this process involves strong electrostatic interactions between partners, which ensure a high affinity and an efficient electron transfer (ET) at the cost of limiting the turnover of the process. In the red lineage, recent kinetic and structural modeling data suggest a different strategy, based on weaker electrostatic interactions between partners, with lower affinity and less efficient ET, but favoring instead the protein exchange and the turnover of the process. Finally, in diatoms the interaction of the acquired green-type Pc with both Cf and PSI may not yet be optimized.
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Affiliation(s)
- Carmen Castell
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, cicCartuja, Sevilla, Spain
| | - Luis A Rodríguez-Lumbreras
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC—Universidad de La Rioja—Gobierno de La Rioja, Logroño, Spain
| | - Manuel Hervás
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, cicCartuja, Sevilla, Spain
| | - Juan Fernández-Recio
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC—Universidad de La Rioja—Gobierno de La Rioja, Logroño, Spain
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Hippler M, Nelson N. The Plasticity of Photosystem I. PLANT & CELL PHYSIOLOGY 2021; 62:1073-1081. [PMID: 33768246 DOI: 10.1093/pcp/pcab046] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
Most of life's energy comes from sunlight, and thus, photosynthesis underpins the survival of virtually all life forms. The light-driven electron transfer at photosystem I (PSI) is certainly the most important generator of reducing power at the cellular level and thereby largely determines the global amount of enthalpy in living systems (Nelson 2011). The PSI is a light-driven plastocyanin:ferredoxin oxidoreductase, which is embedded into thylakoid membranes of cyanobacteria and chloroplasts of eukaryotic photosynthetic organism. Structural determination of complexes of the photosynthetic machinery is vital for the understanding of its mode of action. Here, we describe new structural and functional insights into PSI and associated light-harvesting proteins, with a focus on the plasticity of PSI.
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Affiliation(s)
- Michael Hippler
- Institute of Plant Biology and Biotechnology, University of Münster, Münster 48143, Germany
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nathan Nelson
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Japan
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8
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Gisriel CJ, Azai C, Cardona T. Recent advances in the structural diversity of reaction centers. PHOTOSYNTHESIS RESEARCH 2021; 149:329-343. [PMID: 34173168 PMCID: PMC8452559 DOI: 10.1007/s11120-021-00857-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
Photosynthetic reaction centers (RC) catalyze the conversion of light to chemical energy that supports life on Earth, but they exhibit substantial diversity among different phyla. This is exemplified in a recent structure of the RC from an anoxygenic green sulfur bacterium (GsbRC) which has characteristics that may challenge the canonical view of RC classification. The GsbRC structure is analyzed and compared with other RCs, and the observations reveal important but unstudied research directions that are vital for disentangling RC evolution and diversity. Namely, (1) common themes of electron donation implicate a Ca2+ site whose role is unknown; (2) a previously unidentified lipid molecule with unclear functional significance is involved in the axial ligation of a cofactor in the electron transfer chain; (3) the GsbRC features surprising structural similarities with the distantly-related photosystem II; and (4) a structural basis for energy quenching in the GsbRC can be gleaned that exemplifies the importance of how exposure to oxygen has shaped the evolution of RCs. The analysis highlights these novel avenues of research that are critical for revealing evolutionary relationships that underpin the great diversity observed in extant RCs.
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Affiliation(s)
| | - Chihiro Azai
- College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Tanai Cardona
- Department of Life Sciences, Imperial College London, London, UK
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9
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Structure of plant photosystem I-plastocyanin complex reveals strong hydrophobic interactions. Biochem J 2021; 478:2371-2384. [PMID: 34085703 PMCID: PMC8238519 DOI: 10.1042/bcj20210267] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/28/2021] [Accepted: 06/03/2021] [Indexed: 11/17/2022]
Abstract
Photosystem I is defined as plastocyanin-ferredoxin oxidoreductase. Taking advantage of genetic engineering, kinetic analyses and cryo-EM, our data provide novel mechanistic insights into binding and electron transfer between PSI and Pc. Structural data at 2.74 Å resolution reveals strong hydrophobic interactions in the plant PSI-Pc ternary complex, leading to exclusion of water molecules from PsaA-PsaB/Pc interface once the PSI-Pc complex forms. Upon oxidation of Pc, a slight tilt of bound oxidized Pc allows water molecules to accommodate the space between Pc and PSI to drive Pc dissociation. Such a scenario is consistent with the six times larger dissociation constant of oxidized as compared with reduced Pc and mechanistically explains how this molecular machine optimized electron transfer for fast turnover.
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10
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In vivo electron donation from plastocyanin and cytochrome c 6 to PSI in Synechocystis sp. PCC6803. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148449. [PMID: 34004195 DOI: 10.1016/j.bbabio.2021.148449] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 04/30/2021] [Accepted: 05/14/2021] [Indexed: 11/20/2022]
Abstract
Many cyanobacteria species can use both plastocyanin and cytochrome c6 as lumenal electron carriers to shuttle electrons from the cytochrome b6f to either photosystem I or the respiratory cytochrome c oxidase. In Synechocystis sp. PCC6803 placed in darkness, about 60% of the active PSI centres are bound to a reduced electron donor which is responsible for the fast re-reduction of P700in vivo after a single charge separation. Here, we show that both cytochrome c6 and plastocyanin can bind to PSI in the dark and participate to the fast phase of P700 reduction, but the fraction of pre-bound PSI is smaller in the case of cytochrome c6 than with plastocyanin. Because of the inter-connection of respiration and photosynthesis in cyanobacteria, the inhibition of the cytochrome c oxidase results in the over-reduction of the photosynthetic electron transfer chain in the dark that translates into a lag in the kinetics of P700 oxidation at the onset of light. We show that this is true both with plastocyanin and cytochrome c6, indicating that the partitioning of electron transport between respiration and photosynthesis is regulated in the same way independently of which of the two lumenal electron carriers is present, although the mechanisms of such regulation are yet to be understood.
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11
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Gideon DA, Nirusimhan V, Manoj KM. Are plastocyanin and ferredoxin specific electron carriers or generic redox capacitors? Classical and murburn perspectives on two photosynthetic proteins. J Biomol Struct Dyn 2020; 40:1995-2009. [PMID: 33073701 DOI: 10.1080/07391102.2020.1835715] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In the light reaction of oxygenic photosynthesis, plastocyanin (PC) and ferredoxins (Fd) are small/diffusible redox-active proteins playing key roles in electron transfer/transport phenomena. In the Z-scheme mechanistic purview, they are considered as specific affinity binding-based electron-relay agents, linking the functions of Cytochrome b6f (Cyt. b6f), Photosystem I (PS I) and Fd:NADPH oxidoreductase (FNR). The murburn explanation for photolytic photophosphorylation deems PC/Fd as generic 'redox capacitors', temporally accepting and releasing one-electron equivalents in reaction milieu. Herein, we explore the two theories with respect to structural, distributional and functional aspects of PC/Fd. Amino acid residues located on the surface loci of key patches of PC/Fd vary in electrostatic/contour (topography) signatures. Crystal structures of four different complexes each of Cyt.f-PC and Fd-FNR show little conservation in the contact-surfaces, thereby discrediting 'affinity binding-based electron transfers (ET)' as an evolutionary logic. Further, thermodynamic and kinetic data of wildtype and mutant proteins interactions do not align with Z-scheme. Furthermore, micromolar physiological concentrations of PC and the non-conducive architecture of chloroplasts render the classical model untenable. In the murburn model, as PC is optional, the observation that plants lacking PC survive and grow is justified. Further, the low physiological concentration/distribution of PC in chloroplast lumen/stroma is supported by murburn equilibriums, as higher concentrations would limit electron transfers. Thus, structural evidence, interactive dynamics with redox partners and physiological distribution/role of PC/Fd support the murburn perspective that these proteins serve as generic redox-capacitors in chloroplasts.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Daniel Andrew Gideon
- Department of Biochemistry, Satyamjayatu: The Science & Ethics Foundation, Palakkad, India.,Department of Biotechnology and Bioinformatics, Bishop Heber College (Autonomous), Tiruchirappalli, India
| | - Vijay Nirusimhan
- Department of Biotechnology and Bioinformatics, Bishop Heber College (Autonomous), Tiruchirappalli, India
| | - Kelath Murali Manoj
- Department of Biochemistry, Satyamjayatu: The Science & Ethics Foundation, Palakkad, India
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Terentyev VV, Zharmukhamedov SK. Evolutionary Loss of the Ability of the Photosystem I Primary Electron Donor for the Redox Interaction with Mn-Bicarbonate Complexes. BIOCHEMISTRY (MOSCOW) 2020; 85:697-708. [PMID: 32586233 DOI: 10.1134/s0006297920060073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The structure and functional organization of the photosystem I (PSI) reaction center (RC) donor side has a significant similarity to the reaction centers of purple bacteria (bRCs), despite the fact that they belong to different types of RCs. Moreover, the redox potential values of their primary electron donors are identical (~0.5 V). In our earlier reports [Khorobrykh et al. (2008) Phylos. Trans. R. Soc. B., 363, 1245-1251; Terentyev et al. (2011) Biochemistry (Moscow), 76, 1360-1366; Khorobrykh et al. (2018) ChemBioChem, 14, 1725-1731], we have demonstrated redox interaction of low-potential Mn2+-bicarbonate complexes with bRCs, which might have been one of the first steps in the evolutionary origin of Mn-cluster of the photosystem II water-oxidizing complex that occurred in the Archean (over 3 billion years ago). In this study, we investigated redox interactions between Mn2+-bicarbonate complexes and PSI. Such interactions were almost absent in the original PSI preparations and emerged only in preoxidized PSI preparations containing ~50% oxidized RCs. The interaction between Mn2+-bicarbonate complexes and PSI required increased Mn2+ concentrations, while its dependence on the HCO3- concentration indicated involvement of electroneutral low-potential [Mn(HCO3)2] complex in the process. Analysis of the PSI crystal structure revealed steric hindrances on the RC donor side, which could block the redox interaction between Mn2+-bicarbonate complexes and oxidized primary electron donor. Comparison of structures of RCs from the PSI and ancient RCs from heliobacteria belonging to the same type of RCs suggested that such hindrances should be absent in the primitive PSI in the Archean and allowed to explain their evolutionary origin as a consequence of PSI RCs into the united electron transport chain (ETC) of the photosynthetic membrane that was accompanied by the evolutionary loss of PSI capacity for the redox interaction with Mn2+-bicarbonate complexes.
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Affiliation(s)
- V V Terentyev
- Institute of Basic Biological Problems, Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | - S K Zharmukhamedov
- Institute of Basic Biological Problems, Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
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Antoshvili M, Caspy I, Hippler M, Nelson N. Structure and function of photosystem I in Cyanidioschyzon merolae. PHOTOSYNTHESIS RESEARCH 2019; 139:499-508. [PMID: 29582227 DOI: 10.1007/s11120-018-0501-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 03/21/2018] [Indexed: 05/19/2023]
Abstract
The evolution of photosynthesis from primitive photosynthetic bacteria to higher plants has been driven by the need to adapt to a wide range of environmental conditions. The red alga Cyanidioschyzon merolae is a primitive organism, which is capable of performing photosynthesis in extreme acidic and hot environments. The study of its photosynthetic machinery may provide new insight on the evolutionary path of photosynthesis and on light harvesting and its regulation in eukaryotes. With that aim, the structural and functional properties of the PSI complex were investigated by biochemical characterization, mass spectrometry, and X-ray crystallography. PSI was purified from cells grown at 25 and 42 °C, crystallized and its crystal structure was solved at 4 Å resolution. The structure of C. merolae reveals a core complex with a crescent-shaped structure, formed by antenna proteins. In addition, the structural model shows the position of PsaO and PsaM. PsaG and PsaH are present in plant complex and are missing from the C. merolae model as expected. This paper sheds new light onto the evolution of photosynthesis, which gives a strong indication for the chimerical properties of red algae PSI. The subunit composition of the PSI core from C. merolae and its associated light-harvesting antennae suggests that it is an evolutionary and functional intermediate between cyanobacteria and plants.
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Affiliation(s)
- Maya Antoshvili
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Ido Caspy
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Michael Hippler
- Institute of Plant Biology and Biotechnology, University of Münster, 48143, Münster, Germany
| | - Nathan Nelson
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel.
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14
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Kölsch A, Hejazi M, Stieger KR, Feifel SC, Kern JF, Müh F, Lisdat F, Lokstein H, Zouni A. Insights into the binding behavior of native and non-native cytochromes to photosystem I from Thermosynechococcus elongatus. J Biol Chem 2018; 293:9090-9100. [PMID: 29695502 DOI: 10.1074/jbc.ra117.000953] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/18/2018] [Indexed: 01/09/2023] Open
Abstract
The binding of photosystem I (PS I) from Thermosynechococcus elongatus to the native cytochrome (cyt) c6 and cyt c from horse heart (cyt cHH) was analyzed by oxygen consumption measurements, isothermal titration calorimetry (ITC), and rigid body docking combined with electrostatic computations of binding energies. Although PS I has a higher affinity for cyt cHH than for cyt c6, the influence of ionic strength and pH on binding is different in the two cases. ITC and theoretical computations revealed the existence of unspecific binding sites for cyt cHH besides one specific binding site close to P700 Binding to PS I was found to be the same for reduced and oxidized cyt cHH Based on this information, suitable conditions for cocrystallization of cyt cHH with PS I were found, resulting in crystals with a PS I:cyt cHH ratio of 1:1. A crystal structure at 3.4-Å resolution was obtained, but cyt cHH cannot be identified in the electron density map because of unspecific binding sites and/or high flexibility at the specific binding site. Modeling the binding of cyt c6 to PS I revealed a specific binding site where the distance and orientation of cyt c6 relative to P700 are comparable with cyt c2 from purple bacteria relative to P870 This work provides new insights into the binding modes of different cytochromes to PS I, thus facilitating steps toward solving the PS I-cyt c costructure and a more detailed understanding of natural electron transport processes.
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Affiliation(s)
- Adrian Kölsch
- From the Biophysics of Photosynthesis, Institute for Biology, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115 Berlin, Germany,
| | - Mahdi Hejazi
- From the Biophysics of Photosynthesis, Institute for Biology, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115 Berlin, Germany
| | - Kai R Stieger
- Biosystems Technology, Institute for Applied Life Sciences, University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Sven C Feifel
- Biosystems Technology, Institute for Applied Life Sciences, University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Jan F Kern
- Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Frank Müh
- Department of Theoretical Biophysics, Institute for Theoretical Physics, Johannes Kepler University Linz, Altenberger Strasse 69, 4040 Linz, Austria, and
| | - Fred Lisdat
- Biosystems Technology, Institute for Applied Life Sciences, University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Heiko Lokstein
- Department of Chemical Physics and Optics, Charles University, Ke Karlovu 3, CZ-121 16 Praha 2, Czech Republic
| | - Athina Zouni
- From the Biophysics of Photosynthesis, Institute for Biology, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115 Berlin, Germany,
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Gisriel C, Sarrou I, Ferlez B, Golbeck JH, Redding KE, Fromme R. Structure of a symmetric photosynthetic reaction center-photosystem. Science 2017; 357:1021-1025. [PMID: 28751471 DOI: 10.1126/science.aan5611] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 07/19/2017] [Indexed: 11/02/2022]
Abstract
Reaction centers are pigment-protein complexes that drive photosynthesis by converting light into chemical energy. It is believed that they arose once from a homodimeric protein. The symmetry of a homodimer is broken in heterodimeric reaction-center structures, such as those reported previously. The 2.2-angstrom resolution x-ray structure of the homodimeric reaction center-photosystem from the phototroph Heliobacterium modesticaldum exhibits perfect C2 symmetry. The core polypeptide dimer and two small subunits coordinate 54 bacteriochlorophylls and 2 carotenoids that capture and transfer energy to the electron transfer chain at the center, which performs charge separation and consists of 6 (bacterio)chlorophylls and an iron-sulfur cluster; unlike other reaction centers, it lacks a bound quinone. This structure preserves characteristics of the ancestral reaction center, providing insight into the evolution of photosynthesis.
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Affiliation(s)
- Christopher Gisriel
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Iosifina Sarrou
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg, Germany
| | - Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.,Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.,Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ 85287, USA
| | - Raimund Fromme
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA. .,Center of Applied Structural Discovery, Biodesign Institute, Tempe, AZ 85287, USA
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Bernal-Bayard P, Pallara C, Carmen Castell M, Molina-Heredia FP, Fernández-Recio J, Hervás M, Navarro JA. Interaction of photosystem I from Phaeodactylum tricornutum with plastocyanins as compared with its native cytochrome c6: Reunion with a lost donor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1549-59. [DOI: 10.1016/j.bbabio.2015.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/02/2015] [Accepted: 09/20/2015] [Indexed: 11/17/2022]
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17
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Roitman S, Flores-Uribe J, Philosof A, Knowles B, Rohwer F, Ignacio-Espinoza JC, Sullivan MB, Cornejo-Castillo FM, Sánchez P, Acinas SG, Dupont CL, Béjà O. Closing the gaps on the viral photosystem-I psaDCAB gene organization. Environ Microbiol 2015; 17:5100-8. [PMID: 26310718 PMCID: PMC5019241 DOI: 10.1111/1462-2920.13036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/20/2015] [Indexed: 11/30/2022]
Abstract
Marine photosynthesis is largely driven by cyanobacteria, namely Synechococcus and Prochlorococcus. Genes encoding for photosystem (PS) I and II reaction centre proteins are found in cyanophages and are believed to increase their fitness. Two viral PSI gene arrangements are known, psaJF→C→A→B→K→E→D and psaD→C→A→B. The shared genes between these gene cassettes and their encoded proteins are distinguished by %G + C and protein sequence respectively. The data on the psaD→C→A→B gene organization were reported from only two partial gene cassettes coming from Global Ocean Sampling stations in the Pacific and Indian oceans. Now we have extended our search to 370 marine stations from six metagenomic projects. Genes corresponding to both PSI gene arrangements were detected in the Pacific, Indian and Atlantic oceans, confined to a strip along the equator (30°N and 30°S). In addition, we found that the predicted structure of the viral PsaA protein from the psaD→C→A→B organization contains a lumenal loop conserved in PsaA proteins from Synechococcus, but is completely absent in viral PsaA proteins from the psaJF→C→A→B→K→E→D gene organization and most Prochlorococcus strains. This may indicate a co-evolutionary scenario where cyanophages containing either of these gene organizations infect cyanobacterial ecotypes biogeographically restricted to the 30°N and 30°S equatorial strip.
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Affiliation(s)
- Sheila Roitman
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - José Flores-Uribe
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Alon Philosof
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Ben Knowles
- Department of Biology, San Diego State University, San Diego, CA, USA
| | - Forest Rohwer
- Department of Biology, San Diego State University, San Diego, CA, USA
| | | | - Matthew B Sullivan
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA
| | | | - Pablo Sánchez
- Departament of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Silvia G Acinas
- Departament of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Chris L Dupont
- Microbial and Environmental Genomics Group, J Craig Venter Institute, San Diego, CA, USA
| | - Oded Béjà
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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18
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Baker DR, Simmerman RF, Sumner JJ, Bruce BD, Lundgren CA. Photoelectrochemistry of photosystem I bound in nafion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13650-13655. [PMID: 25341002 DOI: 10.1021/la503132h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Developing a solid state Photosystem I (PSI) modified electrode is attractive for photoelectrochemical applications because of the quantum yield of PSI, which approaches unity in the visible spectrum. Electrodes are constructed using a Nafion film to encapsulate PSI as well as the hole-scavenging redox mediator Os(bpy)2Cl2. The photoactive electrodes generate photocurrents of 4 μA/cm(2) when illuminated with 1.4 mW/cm(2) of 676 nm band-pass filtered light. Methyl viologen (MV(2+)) is present in the electrolyte to scavenge photoelectrons from PSI in the Nafion film and transport charges to the counter electrode. Because MV(2+) is positively charged in both reduced and oxidized states, it is able to diffuse through the cation permeable channels of Nafion. Photocurrent is produced when the working electrode is set to voltages negative of the Os(3+)/Os(2+) redox potential. Charge transfer through the Nafion film and photohole scavenging at the PSI luminal surface by Os(bpy)2Cl2 depends on the reduction of Os redox centers to Os(2+) via hole scavenging from PSI. The optimal film densities of Nafion (10 μg/cm(2) Nafion) and PSI (100 μg/cm(2) PSI) are determined to provide the highest photocurrents. These optimal film densities force films to be thin to allow the majority of PSI to have productive electrical contact with the backing electrode.
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Affiliation(s)
- David R Baker
- U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, United States
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Harris BJ, Cheng X, Frymier P. All-atom molecular dynamics simulation of a photosystem i/detergent complex. J Phys Chem B 2014; 118:11633-45. [PMID: 25233289 DOI: 10.1021/jp507157e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
All-atom molecular dynamics (MD) simulation was used to investigate the solution structure and dynamics of the photosynthetic pigment-protein complex photosystem I (PSI) from Thermosynechococcus elongatus embedded in a toroidal belt of n-dodecyl-β-d-maltoside (DDM) detergent. Evaluation of root-mean-square deviations (RMSDs) relative to the known crystal structure show that the protein complex surrounded by DDM molecules is stable during the 200 ns simulation time, and root-mean-square fluctuation (RMSF) analysis indicates that regions of high local mobility correspond to solvent-exposed regions such as turns in the transmembrane α-helices and flexible loops on the stromal and lumenal faces. Comparing the protein-detergent complex to a pure detergent micelle, the detergent surrounding the PSI trimer is found to be less densely packed but with more ordered detergent tails, contrary to what is seen in most lipid bilayer models. We also investigated any functional implications for the observed conformational dynamics and protein-detergent interactions, discovering interesting structural changes in the psaL subunits associated with maintaining the trimeric structure of the protein. Importantly, we find that the docking of soluble electron mediators such as cytochrome c6 and ferredoxin to PSI is not significantly impacted by the solubilization of PSI in detergent.
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Affiliation(s)
- Bradley J Harris
- Department of Chemical and Biomolecular Engineering, ‡Department of Biochemistry and Cellular and Molecular Biology, §Sustainable Energy Education and Research Center, and ∥Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee , Knoxville, Tennessee 37996, United States
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Bernal-Bayard P, Molina-Heredia FP, Hervás M, Navarro JA. Photosystem I Reduction in Diatoms: As Complex as the Green Lineage Systems but Less Efficient. Biochemistry 2013; 52:8687-95. [DOI: 10.1021/bi401344f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Pilar Bernal-Bayard
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla & CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Fernando P. Molina-Heredia
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla & CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Manuel Hervás
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla & CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - José A. Navarro
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla & CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
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21
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Kuhlgert S, Drepper F, Fufezan C, Sommer F, Hippler M. Residues PsaB Asp612 and PsaB Glu613 of photosystem I confer pH-dependent binding of plastocyanin and cytochrome c(6). Biochemistry 2012; 51:7297-303. [PMID: 22920401 DOI: 10.1021/bi300898j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The binding and electron transfer between plastocyanin (pc) or cytochrome c(6) (cyt c(6)) and photosystem I (PSI) can be described by hydrophobic as well as electrostatic interactions. The two α helices, l and l' in PsaB and PsaA, respectively, are involved in forming the hydrophobic interaction site at the oxidizing site of PSI. To obtain mechanistic insights into the function of the two negatively charged residues D612 and E613, present in α helix l of PsaB, we exchanged both residues by site-directed mutagenesis with His and transformed a PsaB deficient mutant of Chlamydomonas reinhardtii. Flash-induced absorption spectroscopy revealed that PSI harboring the changes D612H and E613H had a high affinity toward binding of the electron donors and possessed an altered pH dependence of electron transfer with pc and cyt c(6). Despite optimized binding and electron transfer between the altered PSI and its electron donors, the mutant strain PsaB-D612H/E613H exhibited a strong light sensitive growth phenotype, indicating that decelerated turnover between pc/cyt c(6) and PSI with respect to electron transfer is deleterious to the cells.
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Affiliation(s)
- Sebastian Kuhlgert
- Institute of Plant Biology and Biotechnology, University of Muenster, Muenster, Germany
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22
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Reyes-Sosa FM, Gil-Martínez J, Molina-Heredia FP. Cytochrome c6-like protein as a putative donor of electrons to photosystem I in the cyanobacterium Nostoc sp. PCC 7119. PHOTOSYNTHESIS RESEARCH 2011; 110:61-72. [PMID: 21984388 DOI: 10.1007/s11120-011-9694-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 09/22/2011] [Indexed: 05/31/2023]
Abstract
Most organisms performing oxygenic photosynthesis contain either cytochrome c(6) or plastocyanin, or both, to transfer electrons from cytochrome b(6)-f to photosystem I. Even though plastocyanin has superseded cytochrome c(6) along evolution, plants contain a modified cytochrome c(6), the so called cytochrome c(6A), whose function still remains unknown. In this article, we describe a second cytochrome c(6) (the so called cytochrome c(6)-like protein), which is found in some cyanobacteria but is phylogenetically more related to plant cytochrome c(6A) than to cyanobacterial cytochrome c(6). In this article, we conclude that the cytochrome c(6)-like protein is a putative electron donor to photosystem I, but does play a role different to that of cytochrome c(6) and plastocyanin as it cannot accept electrons from cytochrome f. The existence of this third electron donor to PSI could explain why some cyanobacteria are able to grow photoautotrophically in the absence of both cytochrome c(6) and plastocyanin. In any way, the Cyt c(6)-like protein from Nostoc sp. PCC 7119 would be potentially utilized for the biohydrogen production, using cell-free photosystem I catalytic nanoparticles.
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Affiliation(s)
- Francisco M Reyes-Sosa
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
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Xu W, Wang Y, Taylor E, Laujac A, Gao L, Savikhin S, Chitnis PR. Mutational analysis of photosystem I of Synechocystis sp. PCC 6803: the role of four conserved aromatic residues in the j-helix of PsaB. PLoS One 2011; 6:e24625. [PMID: 21931782 PMCID: PMC3171458 DOI: 10.1371/journal.pone.0024625] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 08/15/2011] [Indexed: 11/19/2022] Open
Abstract
Photosystem I is the light-driven plastocyanin-ferredoxin oxidoreductase in the photosynthetic electron transfer of cyanobacteria and plants. Two histidyl residues in the symmetric transmembrane helices A-j and B-j provide ligands for the P700 chlorophyll molecules of the reaction center of photosystem I. To determine the role of conserved aromatic residues adjacent to the histidyl molecule in the helix of B-j, we generated six site-directed mutants of the psaB gene in Synechocystis sp. PCC 6803. Three mutant strains with W645C, W643C/A644I and S641C/V642I substitutions could grow photoautotrophically and showed no obvious reduction in the photosystem I activity. Kinetics of P700 re-reduction by plastocyanin remained unaltered in these mutants. In contrast, the strains with H651C/L652M, F649C/G650I and F647C substitutions could not grow under photoautotrophic conditions because those mutants had low photosystem I activity, possibly due to low levels of proteins. A procedure to select spontaneous revertants from the mutants that are incapable to photoautotrophic growth resulted in three revertants that were used in this study. The molecular analysis of the spontaneous revertants suggested that an aromatic residue at F647 and a small residue at G650 may be necessary for maintaining the structural integrity of photosystem I. The (P700⁺-P700) steady-state absorption difference spectrum of the revertant F647Y has a ∼5 nm narrower peak than the recovered wild-type, suggesting that additional hydroxyl group of this revertant may participate in the interaction with the special pair while the photosystem I complexes of the F649C/G650T and H651Q mutants closely resemble the wild-type spectrum. The results presented here demonstrate that the highly conserved residues W645, W643 and F649 are not critical for maintaining the integrity and in mediating electron transport from plastocyanin to photosystem I. Our data suggest that an aromatic residue is required at position of 647 for structural integrity and/or function of photosystem I.
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Affiliation(s)
- Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana, United States of America
| | - Yingchun Wang
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing, China
| | - Eric Taylor
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana, United States of America
| | - Amelie Laujac
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana, United States of America
| | - Liyan Gao
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing, China
| | - Sergei Savikhin
- Department of Physics, Purdue University, West Lafayette, Indiana, United States of America
| | - Parag R. Chitnis
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
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Winkler M, Kawelke S, Happe T. Light driven hydrogen production in protein based semi-artificial systems. BIORESOURCE TECHNOLOGY 2011; 102:8493-8500. [PMID: 21696949 DOI: 10.1016/j.biortech.2011.05.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 05/04/2011] [Accepted: 05/08/2011] [Indexed: 05/31/2023]
Abstract
Photobiological hydrogen production has recently attracted interest in terms of being a potential source for an alternative energy carrier. Especially the natural light driven hydrogen metabolism of unicellular green algae appears as an attractive blueprint for a clean and potentially unlimited dihydrogen source. However, the efficiency of in vivo systems is limited by physiological and evolutionary constraints and scientists only begin to understand the regulatory networks influencing cellular hydrogen production. A growing number of projects aim at circumventing these limitations by focusing on semi-artificial systems. They reconstitute parts of the native electron transfer chains in vitro, combining photosystem I as a photoactive element with a proton reducing catalytic element such as hydrogenase enzymes or noble metal nanoparticles. This review summarizes various approaches and discusses limitations that have to be overcome in order to establish economically applicable systems.
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Affiliation(s)
- Martin Winkler
- Ruhr-Universität Bochum, Fakultät für Biologie und Biotechnologie, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, 44780 Bochum, Germany
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Nakamura A, Suzawa T, Kato Y, Watanabe T. Species Dependence of the Redox Potential of the Primary Electron Donor P700 in Photosystem I of Oxygenic Photosynthetic Organisms Revealed by Spectroelectrochemistry. ACTA ACUST UNITED AC 2011; 52:815-23. [DOI: 10.1093/pcp/pcr034] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Sommer F, Kropat J, Malasarn D, Grossoehme NE, Chen X, Giedroc DP, Merchant SS. The CRR1 nutritional copper sensor in Chlamydomonas contains two distinct metal-responsive domains. THE PLANT CELL 2010; 22:4098-113. [PMID: 21131558 PMCID: PMC3027176 DOI: 10.1105/tpc.110.080069] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Revised: 10/02/2010] [Accepted: 11/15/2010] [Indexed: 05/18/2023]
Abstract
Copper response regulator 1 (CRR1), an SBP-domain transcription factor, is a global regulator of nutritional copper signaling in Chlamydomonas reinhardtii and activates genes necessary during periods of copper deficiency. We localized Chlamydomonas CRR1 to the nucleus in mustard (Sinapis alba) seedlings, a location consistent with its function as a transcription factor. The Zn binding SBP domain of CRR1 binds copper ions in vitro. Cu(I) can replace Zn(II), but the Cu(II) form is unstable. The DNA binding activity is inhibited in vitro by Cu(II) or Hg(II) ions, which also prevent activation of transcription in vivo, but not by Co(II) or Ni(II), which have no effect in vivo. Copper inhibition of DNA binding is reduced by mutation of a conserved His residue. These results implicate the SBP domain in copper sensing. Deletion of a C-terminal metallothionein-like Cys-rich domain impacted neither nutritional copper signaling nor the effect of mercuric supplementation, but rendered CRR1 insensitive to hypoxia and to nickel supplementation, which normally activate the copper deficiency regulon in wild-type cells. Strains carrying the crr1-ΔCys allele upregulate ZRT genes and hyperaccumulate Zn(II), suggesting that the effect of nickel ions may be revealing a role for the C-terminal domain of CRR1 in zinc homeostasis in Chlamydomonas.
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Affiliation(s)
- Frederik Sommer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
- Max Planck Institute of Molecular Plant Physiology-Golm, 14476 Potsdam, Germany
| | - Janette Kropat
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
| | - Davin Malasarn
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
| | | | - Xiaohua Chen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - David P. Giedroc
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102
| | - Sabeeha S. Merchant
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
- Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095-1569
- Address correspondence to
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Busch A, Hippler M. The structure and function of eukaryotic photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:864-77. [PMID: 20920463 DOI: 10.1016/j.bbabio.2010.09.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 09/20/2010] [Accepted: 09/28/2010] [Indexed: 12/27/2022]
Abstract
Eukaryotic photosystem I consists of two functional moieties: the photosystem I core, harboring the components for the light-driven charge separation and the subsequent electron transfer, and the peripheral light-harvesting complex (LHCI). While the photosystem I-core remained highly conserved throughout the evolution, with the exception of the oxidizing side of photosystem I, the LHCI complex shows a high degree of variability in size, subunits composition and bound pigments, which is due to the large variety of different habitats photosynthetic organisms dwell in. Besides summarizing the most current knowledge on the photosystem I-core structure, we will discuss the composition and structure of the LHCI complex from different eukaryotic organisms, both from the red and the green clade. Furthermore, mechanistic insights into electron transfer between the donor and acceptor side of photosystem I and its soluble electron transfer carrier proteins will be given. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts.
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Affiliation(s)
- Andreas Busch
- Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
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Santabarbara S, Redding KE, Rappaport F. Temperature Dependence of the Reduction of P700+ by Tightly Bound Plastocyanin in Vivo. Biochemistry 2009; 48:10457-66. [DOI: 10.1021/bi901052c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefano Santabarbara
- Department of Chemistry and Biochemistry, Arizona State University, 1711 South Rural Road, Tempe, Arizona 85287
- Institut de Biologie Physico-Chimique, UMR7141 CNRS-Universite Paris 6, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Kevin E. Redding
- Department of Chemistry and Biochemistry, Arizona State University, 1711 South Rural Road, Tempe, Arizona 85287
| | - Fabrice Rappaport
- Institut de Biologie Physico-Chimique, UMR7141 CNRS-Universite Paris 6, 13 Rue Pierre et Marie Curie, 75005 Paris, France
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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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Amunts A, Nelson N. Functional organization of a plant Photosystem I: evolution of a highly efficient photochemical machine. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:228-37. [PMID: 18272382 DOI: 10.1016/j.plaphy.2007.12.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Indexed: 05/05/2023]
Abstract
Despite its enormous complexity, a plant Photosystem I (PSI) is arguably the most efficient nano-photochemical machine in Nature. It emerged as a homodimeric structure containing several chlorophyll molecules over 3.5 billion years ago, and has perfected its photoelectric properties ever since. The recently determined structure of plant PSI, which is at the top of the evolutionary tree of this kind of complexes, provided the first relatively high-resolution structural model of the supercomplex containing a reaction center (RC) and a peripheral antenna (LHCI) complexes. The RC is highly homologous to that of the cyanobacterial PSI and maintains the position of most transmembrane helices and chlorophylls during 1.5 years of separate evolution. The LHCI is composed of four nuclear gene products (Lhca1-Lhca4) that are unique among the chlorophyll a/b binding proteins in their pronounced long-wavelength absorbance and their assembly into dimers. In this respect, we describe structural elements, which establish the biological significance of a plant PSI and discuss structural variance from the cyanobacterial version. The present comprehensive structural analysis summarizes our current state of knowledge, providing the first glimpse at the architecture of this highly efficient photochemical machine at the atomic level.
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Affiliation(s)
- Alexey Amunts
- Biochemistry Department, The George S. Wise Faculty of Life Sciences, The Daniella Rich Institute for Structural Biology, Tel Aviv University, Sherman Building, Room 531, Tel Aviv 69978, Israel.
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Sommer F, Drepper F, Haehnel W, Hippler M. Identification of precise electrostatic recognition sites between cytochrome c6 and the photosystem I subunit PsaF using mass spectrometry. J Biol Chem 2006; 281:35097-103. [PMID: 16984911 DOI: 10.1074/jbc.m607384200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The reduction of the photo-oxidized special chlorophyll pair P700 of photosystem I (PSI) in the photosynthetic electron transport chain of eukaryotic organisms is facilitated by the soluble copper-containing protein plastocyanin (pc). In the absence of copper, pc is functionally replaced by the heme-containing protein cytochrome c6 (cyt c6) in the green alga Chlamydomonas reinhardtii. Binding and electron transfer between both donors and PSI follows a two-step mechanism that depends on electrostatic and hydrophobic recognition between the partners. Although the electrostatic and hydrophobic recognition sites on pc and PSI are well known, the precise electrostatic recognition site on cyt c6 is unknown. To specify the interaction sites on a molecular level, we cross-linked cyt c6 and PSI using a zero-length cross-linker and obtained a cross-linked complex competent in fast and efficient electron transfer. As shown previously, cyt c6 cross-links specifically with the PsaF subunit of PSI. Mass spectrometric analysis of tryptic peptides from the cross-linked product revealed specific interaction sites between residues Lys27 of PsaF and Glu69 of cyt c6 and between Lys23 of PsaF and Glu69/Glu70 of cyt c6. Using these new data, we present a molecular model of the intermolecular electron transfer complex between eukaryotic cyt c6 and PSI.
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Affiliation(s)
- Frederik Sommer
- Institute of Plant Science, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Abstract
Oxygenic photosynthesis, the principal converter of sunlight into chemical energy on earth, is catalyzed by four multi-subunit membrane-protein complexes: photosystem I (PSI), photosystem II (PSII), the cytochrome b(6)f complex, and F-ATPase. PSI generates the most negative redox potential in nature and largely determines the global amount of enthalpy in living systems. PSII generates an oxidant whose redox potential is high enough to enable it to oxidize H(2)O, a substrate so abundant that it assures a practically unlimited electron source for life on earth. During the last century, the sophisticated techniques of spectroscopy, molecular genetics, and biochemistry were used to reveal the structure and function of the two photosystems. The new structures of PSI and PSII from cyanobacteria, algae, and plants has shed light not only on the architecture and mechanism of action of these intricate membrane complexes, but also on the evolutionary forces that shaped oxygenic photosynthesis.
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Affiliation(s)
- Nathan Nelson
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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Finazzi G, Sommer F, Hippler M. Release of oxidized plastocyanin from photosystem I limits electron transfer between photosystem I and cytochrome b6f complex in vivo. Proc Natl Acad Sci U S A 2005; 102:7031-6. [PMID: 15870213 PMCID: PMC1100731 DOI: 10.1073/pnas.0406288102] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We used fast absorbance spectroscopy to investigate in vivo binding dynamics and electron transfer between plastocyanin (pc) and photosystem I (PSI), and cytochrome (cyt) f oxidation kinetics in Chlamydomonas reinhardtii mutants in which either the binding or the release of pc from PSI was diminished. Under single flash-excitation conditions, electron flow between PSI and the cyt complex was not affected by a 5-fold lowering of the binding affinity of pc to PSI, as induced by a mutation replacing the tryptophan-651 of the PsaA subunit by a serine residue (PsaA-W651S). On the other hand, electron flow from PSI to the cyt b(6)f complex was very sensitive to a 2- to 3-fold decrease in the rate of pc release from PSI, obtained by replacing the glutamic acid residue 613 of the PsaB subunit with glutamine (PsaB-E613N). Thus, our data indicate that under these experimental conditions the release of oxidized pc limits electron transfer between cyt b(6)f complex and PSI in vivo.
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Affiliation(s)
- Giovanni Finazzi
- Unité Mixte de Recherche 7141 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, 75005 Paris, France.
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Zygadlo A, Jensen PE, Leister D, Scheller HV. Photosystem I lacking the PSI-G subunit has a higher affinity for plastocyanin and is sensitive to photodamage. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1708:154-63. [PMID: 15953472 DOI: 10.1016/j.bbabio.2005.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 02/09/2005] [Accepted: 02/17/2005] [Indexed: 11/26/2022]
Abstract
PSI-G is an 11 kDa subunit of PSI in photosynthetic eukaryotes. Arabidopsis thaliana plants devoid of PSI-G have a decreased PSI content and an increased activity of NADP(+) photoreduction in vitro but otherwise no obvious phenotype. To investigate the biochemical basis for the increased activity, the kinetic parameters of the reaction between PSI and plastocyanin were determined. PSI-G clearly plays a role in the affinity for plastocyanin since the dissociation constant (K(D)) is only 12 muM in the absence of PSI-G compared to 32 muM for the wild type. On the physiological level, plants devoid of PSI-G have a more reduced Q(A). This indicates that the decreased PSI content is due to unstable PSI rather than an adaptation to the increased activity. In agreement with this indication of decreased stability, plants devoid of PSI-G were found to be more photo-inhibited both at low temperature and after high light treatment. The decreased PSI stability was confirmed in vitro by measuring PSI activity after illumination of a thylakoid suspension which clearly showed a faster decrease in PSI activity in the thylakoids lacking PSI-G. Light response of the P700 redox state in vivo showed that in the absence of PSI-G, P700 is more reduced at low light intensities. We conclude that PSI-G is involved in the binding dynamics of plastocyanin to PSI and that PSI-G is important for the stability of the PSI complex.
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Affiliation(s)
- Agnieszka Zygadlo
- Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, 40 Thorvaldsensvej, DK-1871 Frederiksberg C, Denmark
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Grotjohann I, Fromme P. Structure of cyanobacterial photosystem I. PHOTOSYNTHESIS RESEARCH 2005; 85:51-72. [PMID: 15977059 DOI: 10.1007/s11120-005-1440-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2004] [Accepted: 01/28/2005] [Indexed: 05/03/2023]
Abstract
Photosystem I is one of the most fascinating membrane protein complexes for which a structure has been determined. It functions as a bio-solar energy converter, catalyzing one of the first steps of oxygenic photosynthesis. It captures the light of the sun by means of a large antenna system, consisting of chlorophylls and carotenoids, and transfers the energy to the center of the complex, driving the transmembrane electron transfer from plastoquinone to ferredoxin. Cyanobacterial Photosystem I is a trimer consisting of 36 proteins to which 381 cofactors are non-covalently attached. This review discusses the complex function of Photosystem I based on the structure of the complex at 2.5 A resolution as well as spectroscopic and biochemical data.
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