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Tikhonov AN. The cytochrome b 6f complex: plastoquinol oxidation and regulation of electron transport in chloroplasts. PHOTOSYNTHESIS RESEARCH 2024; 159:203-227. [PMID: 37369875 DOI: 10.1007/s11120-023-01034-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
In oxygenic photosynthetic systems, the cytochrome b6f (Cytb6f) complex (plastoquinol:plastocyanin oxidoreductase) is a heart of the hub that provides connectivity between photosystems (PS) II and I. In this review, the structure and function of the Cytb6f complex are briefly outlined, being focused on the mechanisms of a bifurcated (two-electron) oxidation of plastoquinol (PQH2). In plant chloroplasts, under a wide range of experimental conditions (pH and temperature), a diffusion of PQH2 from PSII to the Cytb6f does not limit the intersystem electron transport. The overall rate of PQH2 turnover is determined mainly by the first step of the bifurcated oxidation of PQH2 at the catalytic site Qo, i.e., the reaction of electron transfer from PQH2 to the Fe2S2 cluster of the high-potential Rieske iron-sulfur protein (ISP). This point has been supported by the quantum chemical analysis of PQH2 oxidation within the framework of a model system including the Fe2S2 cluster of the ISP and surrounding amino acids, the low-potential heme b6L, Glu78 and 2,3,5-trimethylbenzoquinol (the tail-less analog of PQH2). Other structure-function relationships and mechanisms of electron transport regulation of oxygenic photosynthesis associated with the Cytb6f complex are briefly outlined: pH-dependent control of the intersystem electron transport and the regulatory balance between the operation of linear and cyclic electron transfer chains.
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Affiliation(s)
- Alexander N Tikhonov
- Department of Biophysics, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russian Federation, 119991.
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2
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Lan Y, Chen Q, Mi H. NdhS interacts with cytochrome b 6 f to form a complex in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:706-716. [PMID: 37493543 DOI: 10.1111/tpj.16398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/27/2023] [Accepted: 07/05/2023] [Indexed: 07/27/2023]
Abstract
Cyclic electron transport (CET) around photosystem I (PSI) is crucial for photosynthesis to perform photoprotection and sustain the balance of ATP and NADPH. However, the critical component of CET, cyt b6 f complex (cyt b6 f), functions in CET has yet to be understood entirely. In this study, we found that NdhS, a subunit of NADPH dehydrogenase-like (NDH) complex, interacted with cyt b6 f to form a complex in Arabidopsis. This interaction depended on the N-terminal extension of NdhS, which was conserved in eukaryotic plants but defective in prokaryotic algae. The migration of NdhS was much more in cyt b6 f than in PSI-NDH super-complex. Based on these results, we suggested that NdhS and NADP+ oxidoreductase provide a docking domain for the mobile electron carrier ferredoxin to transfer electrons to the plastoquinone pool via cyt b6 f in eukaryotic photosynthesis.
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Affiliation(s)
- Yixin Lan
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences / Institute of Plant Physiology and Ecology, 300 Fenglin Road, Shanghai, 200032, P.R. China
| | - Qi Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences / Institute of Plant Physiology and Ecology, 300 Fenglin Road, Shanghai, 200032, P.R. China
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences / Institute of Plant Physiology and Ecology, 300 Fenglin Road, Shanghai, 200032, P.R. China
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Heyno E, Ermakova M, Lopez‐Calcagno PE, Woodford R, Brown KL, Matthews JSA, Osmond B, Raines CA, von Caemmerer S. Rieske FeS overexpression in tobacco provides increased abundance and activity of cytochrome b 6 f. PHYSIOLOGIA PLANTARUM 2022; 174:e13803. [PMID: 36259085 PMCID: PMC9828649 DOI: 10.1111/ppl.13803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/04/2022] [Accepted: 10/14/2022] [Indexed: 05/31/2023]
Abstract
Photosynthesis is fundamental for plant growth and yield. The cytochrome b6 f complex catalyses a rate-limiting step in thylakoid electron transport and therefore represents an important point of regulation of photosynthesis. Here we show that overexpression of a single core subunit of cytochrome b6 f, the Rieske FeS protein, led to up to a 40% increase in the abundance of the complex in Nicotiana tabacum (tobacco) and was accompanied by an enhanced in vitro cytochrome f activity, indicating a full functionality of the complex. Analysis of transgenic plants overexpressing Rieske FeS by the light-induced fluorescence transients technique revealed a more oxidised primary quinone acceptor of photosystem II (QA ) and plastoquinone pool and faster electron transport from the plastoquinone pool to photosystem I upon changes in irradiance, compared to control plants. A faster establishment of qE , the energy-dependent component of nonphotochemical quenching, in transgenic plants suggests a more rapid buildup of the transmembrane proton gradient, also supporting the increased in vivo cytochrome b6 f activity. However, there was no consistent increase in steady-state rates of electron transport or CO2 assimilation in plants overexpressing Rieske FeS grown in either laboratory conditions or field trials, suggesting that the in vivo activity of the complex was only transiently increased upon changes in irradiance. Our results show that overexpression of Rieske FeS in tobacco enhances the abundance of functional cytochrome b6 f and may have the potential to increase plant productivity if combined with other traits.
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Affiliation(s)
- Eiri Heyno
- Centre of Excellence for Translational Photosynthesis, Division of Plant ScienceResearch School of Biology, The Australian National UniversityActonAustralian Capital TerritoryAustralia
| | - Maria Ermakova
- Centre of Excellence for Translational Photosynthesis, Division of Plant ScienceResearch School of Biology, The Australian National UniversityActonAustralian Capital TerritoryAustralia
- School of Biological SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Patricia E. Lopez‐Calcagno
- School of Biological SciencesUniversity of EssexColchesterUK
- School of Natural and Environmental SciencesNewcastle UniversityNewcastleUK
| | - Russell Woodford
- Centre of Excellence for Translational Photosynthesis, Division of Plant ScienceResearch School of Biology, The Australian National UniversityActonAustralian Capital TerritoryAustralia
| | - Kenny L. Brown
- School of Biological SciencesUniversity of EssexColchesterUK
| | | | - Barry Osmond
- Centre of Excellence for Translational Photosynthesis, Division of Plant ScienceResearch School of Biology, The Australian National UniversityActonAustralian Capital TerritoryAustralia
| | | | - Susanne von Caemmerer
- Centre of Excellence for Translational Photosynthesis, Division of Plant ScienceResearch School of Biology, The Australian National UniversityActonAustralian Capital TerritoryAustralia
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Cryo-EM structures of the Synechocystis sp. PCC 6803 cytochrome b6f complex with and without the regulatory PetP subunit. Biochem J 2022; 479:1487-1503. [PMID: 35726684 PMCID: PMC9342900 DOI: 10.1042/bcj20220124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 06/01/2022] [Accepted: 06/21/2022] [Indexed: 11/17/2022]
Abstract
In oxygenic photosynthesis, the cytochrome b6f (cytb6f) complex links the linear electron transfer (LET) reactions occurring at photosystems I and II and generates a transmembrane proton gradient via the Q-cycle. In addition to this central role in LET, cytb6f also participates in a range of processes including cyclic electron transfer (CET), state transitions and photosynthetic control. Many of the regulatory roles of cytb6f are facilitated by auxiliary proteins that differ depending upon the species, yet because of their weak and transient nature the structural details of these interactions remain unknown. An apparent key player in the regulatory balance between LET and CET in cyanobacteria is PetP, a ∼10 kDa protein that is also found in red algae but not in green algae and plants. Here, we used cryogenic electron microscopy to determine the structure of the Synechocystis sp. PCC 6803 cytb6f complex in the presence and absence of PetP. Our structures show that PetP interacts with the cytoplasmic side of cytb6f, displacing the C-terminus of the PetG subunit and shielding the C-terminus of cytochrome b6, which binds the heme cn cofactor that is suggested to mediate CET. The structures also highlight key differences in the mode of plastoquinone binding between cyanobacterial and plant cytb6f complexes, which we suggest may reflect the unique combination of photosynthetic and respiratory electron transfer in cyanobacterial thylakoid membranes. The structure of cytb6f from a model cyanobacterial species amenable to genetic engineering will enhance future site-directed mutagenesis studies of structure-function relationships in this crucial ET complex.
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Vershubskii AV, Tikhonov AN. Structural and Functional Aspects of Electron Transport Thermoregulation and ATP Synthesis in Chloroplasts. BIOCHEMISTRY (MOSCOW) 2021; 86:92-104. [PMID: 33705285 DOI: 10.1134/s0006297921010090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The review is focused on analysis of the mechanisms of temperature-dependent regulation of electron transport and ATP synthesis in chloroplasts of higher plants. Importance of photosynthesis thermoregulation is determined by the fact that plants are ectothermic organisms, whose own temperature depends on the ambient temperature. The review discusses the effects of temperature on the following processes in thylakoid membranes: (i) photosystem 2 activity and plastoquinone reduction; (ii) electron transfer from plastoquinol (via the cytochrome b6f complex and plastocyanin) to photosystem 1; (iii) transmembrane proton transfer; and (iv) ATP synthesis. The data on the relationship between the functional properties of chloroplasts (photosynthetic transfer of electrons and protons, functioning of ATP synthase) and structural characteristics of membrane lipids (fluidity) obtained by electron paramagnetic resonance studies are presented.
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Malone LA, Proctor MS, Hitchcock A, Hunter CN, Johnson MP. Cytochrome b 6f - Orchestrator of photosynthetic electron transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148380. [PMID: 33460588 DOI: 10.1016/j.bbabio.2021.148380] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 01/06/2021] [Accepted: 01/09/2021] [Indexed: 11/18/2022]
Abstract
Cytochrome b6f (cytb6f) lies at the heart of the light-dependent reactions of oxygenic photosynthesis, where it serves as a link between photosystem II (PSII) and photosystem I (PSI) through the oxidation and reduction of the electron carriers plastoquinol (PQH2) and plastocyanin (Pc). A mechanism of electron bifurcation, known as the Q-cycle, couples electron transfer to the generation of a transmembrane proton gradient for ATP synthesis. Cytb6f catalyses the rate-limiting step in linear electron transfer (LET), is pivotal for cyclic electron transfer (CET) and plays a key role as a redox-sensing hub involved in the regulation of light-harvesting, electron transfer and photosynthetic gene expression. Together, these characteristics make cytb6f a judicious target for genetic manipulation to enhance photosynthetic yield, a strategy which already shows promise. In this review we will outline the structure and function of cytb6f with a particular focus on new insights provided by the recent high-resolution map of the complex from Spinach.
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Affiliation(s)
- Lorna A Malone
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Matthew S Proctor
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Andrew Hitchcock
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Matthew P Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
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Tikhonov AN, Vershubskii AV. Temperature-dependent regulation of electron transport and ATP synthesis in chloroplasts in vitro and in silico. PHOTOSYNTHESIS RESEARCH 2020; 146:299-329. [PMID: 32780309 DOI: 10.1007/s11120-020-00777-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
The significance of temperature-dependent regulation of photosynthetic apparatus (PSA) is determined by the fact that plant temperature changes with environmental temperature. In this work, we present a brief overview of temperature-dependent regulation of photosynthetic processes in class B chloroplasts (thylakoids) and analyze these processes using a computer model that takes into account the key stages of electron and proton transport coupled to ATP synthesis. The rate constants of partial reactions were parametrized on the basis of experimental temperature dependences of partial photosynthetic processes: (1) photosystem II (PSII) turnover and plastoquinone (PQ) reduction, (2) the plastoquinol (PQH2) oxidation by the cytochrome (Cyt) b6f complex, (3) the ATP synthase activity, and (4) the proton leak from the thylakoid lumen. We consider that PQH2 oxidation is the rate-limiting step in the intersystem electron transport. The parametrization of the rate constants of these processes is based on earlier experimental data demonstrating strong correlations between the functional and structural properties of thylakoid membranes that were probed with the lipid-soluble spin labels embedded into the membranes. Within the framework of our model, we could adequately describe a number of experimental temperature dependences of photosynthetic reactions in thylakoids. Computer modeling of electron and proton transport coupled to ATP synthesis supports the notion that PQH2 oxidation by the Cyt b6f complex and proton pumping into the lumen are the basic temperature-dependent processes that determine the overall electron flux from PSII to molecular oxygen and the net ATP synthesis upon variations of temperature. The model describes two branches of the temperature dependence of the post-illumination reduction of [Formula: see text] characterized by different activation energies (about 60 and ≤ 3.5 kJ mol-1). The model predicts the bell-like temperature dependence of ATP formation, which arises from the balance of several factors: (1) the thermo-induced acceleration of electron transport through the Cyt b6f complex, (2) deactivation of PSII photochemistry at sufficiently high temperatures, and (3) acceleration of the passive proton outflow from the thylakoid lumen bypassing the ATP synthase complex. The model describes the temperature dependence of experimentally measured parameter P/2e, determined as the ratio between the rates of ATP synthesis and pseudocyclic electron transport (H2O → PSII → PSI → O2).
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Affiliation(s)
- Alexander N Tikhonov
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia.
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.
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Bhaduri S, Zhang H, Erramilli S, Cramer WA. Structural and functional contributions of lipids to the stability and activity of the photosynthetic cytochrome b 6 f lipoprotein complex. J Biol Chem 2019; 294:17758-17767. [PMID: 31597701 DOI: 10.1074/jbc.ra119.009331] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 10/08/2019] [Indexed: 11/06/2022] Open
Abstract
The photosynthetic cytochrome b 6 f complex, a homodimer containing eight distinct subunits and 26 transmembrane helices per monomer, catalyzes proton-coupled electron transfer across the thylakoid membrane. The 2.5-Å-resolution structure of the complex from the cyanobacterium Nostoc sp. revealed the presence of 23 lipid-binding sites per monomer. Although the crystal structure of the cytochrome b 6 f from a plant source has not yet been solved, the identities of the lipids present in a plant b 6 f complex have previously been determined, indicating that the predominant lipid species are monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), phosphatidylglycerol (PG), and sulfoquinovosyldiacylglycerol (SQDG). Despite the extensive structural analyses of b 6 f-lipid interactions, the basis of the stabilization by lipids remains poorly understood. In the present study, we report on the effect of individual lipids on the structural and functional integrity of the b 6 f complex, purified from Spinacea oleracea It was found that (i) galactolipids (MGDG, DGDG, and SQDG) and phospholipids dilinolenoyl-phosphatidylglycerol (DLPG), 1,2-dioleoylphosphatidylglycerol (DOPG), and 1,2-dioleoyl-sn-glycerol-3-phosphatidylcholine (DOPC) structurally stabilize the complex to varying degrees; (ii) SQDG has a major role in stabilizing the dimeric complex; (iii) the b 6 f complex is stabilized by incorporation into nanodiscs or bicelles; (iv) removal of bound phospholipid by phospholipase A2 inactivates the cytochrome complex; and (v) activity can be restored significantly by the addition of the anionic lipid PG, which is attributed to stabilization of the quinone portal and the hinge region of the iron-sulfur protein.
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Affiliation(s)
- Satarupa Bhaduri
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47906
| | - Huamin Zhang
- SSCI, a Division of Albany Molecular Research Inc., West Lafayette, Indiana 47906
| | - Satchal Erramilli
- Department of Biochemistry and Molecular Biophysics, University of Chicago, Chicago, Illinois 60637
| | - William A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47906
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The cytochrome b6f complex: DFT modeling of the first step of plastoquinol oxidation by the iron-sulfur protein. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2018.01.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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10
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Kóbori TO, Uzumaki T, Kis M, Kovács L, Domonkos I, Itoh S, Krynická V, Kuppusamy SG, Zakar T, Dean J, Szilák L, Komenda J, Gombos Z, Ughy B. Phosphatidylglycerol is implicated in divisome formation and metabolic processes of cyanobacteria. JOURNAL OF PLANT PHYSIOLOGY 2018; 223:96-104. [PMID: 29558689 DOI: 10.1016/j.jplph.2018.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 02/26/2018] [Accepted: 02/27/2018] [Indexed: 06/08/2023]
Abstract
Phosphatidylglycerol is an essential phospholipid for photosynthesis and other cellular processes. We investigated the role of phosphatidylglycerol in cell division and metabolism in a phophatidylglycerol-auxotrophic strain of Synechococcus PCC7942. Here we show that phosphatidylglycerol is essential for the photosynthetic electron transfer and for the oligomerisation of the photosynthetic complexes, notably, we revealed that this lipid is important for non-linear electron transport. Furthermore, we demonstrate that phosphatidylglycerol starvation elevated the expressions of proteins of nitrogen and carbon metabolism. Moreover, we show that phosphatidylglycerol-deficient cells changed the morphology, became elongated, the FtsZ ring did not assemble correctly, and subsequently the division was hindered. However, supplementation with phosphatidylglycerol restored the ring-like structure at the mid-cell region and the normal cell size, demonstrating the phosphatidylglycerol is needed for normal septum formation. Taken together, central roles of phosphatidylglycerol were revealed; it is implicated in the photosynthetic activity, the metabolism and the fission of bacteria.
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Affiliation(s)
- Tímea O Kóbori
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary; Doctoral School of Biology, University of Szeged, H-6726 Szeged, Hungary
| | - Tatsuya Uzumaki
- Center for Gene Research, Nagoya University, Furocyo, Chikusa, Nagoya 464-8607, Japan
| | - Mihály Kis
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Ildikó Domonkos
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Shigeru Itoh
- Center for Gene Research, Nagoya University, Furocyo, Chikusa, Nagoya 464-8607, Japan
| | - Vendula Krynická
- Institute of Microbiology, Center Algatech, Czech Academy of Sciences, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - Saravanan G Kuppusamy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Tomas Zakar
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Jason Dean
- Institute of Microbiology, Center Algatech, Czech Academy of Sciences, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - László Szilák
- Institute of Biology, Savaria Campus, Eötvös Lorand University, Szombathely, H-9700, Hungary
| | - Josef Komenda
- Institute of Microbiology, Center Algatech, Czech Academy of Sciences, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - Zoltán Gombos
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Bettina Ughy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary.
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Abstract
This chapter presents an overview of structural properties of the cytochrome (Cyt) b 6 f complex and its functioning in chloroplasts. The Cyt b 6 f complex stands at the crossroad of photosynthetic electron transport pathways, providing connectivity between Photosystem (PSI) and Photosysten II (PSII) and pumping protons across the membrane into the thylakoid lumen. After a brief review of the chloroplast electron transport chain, the consideration is focused on the structural organization of the Cyt b 6 f complex and its interaction with plastoquinol (PQH2, reduced form of plastoquinone), a mediator of electron transfer from PSII to the Cyt b 6 f complex. The processes of PQH2 oxidation by the Cyt b 6 f complex have been considered within the framework of the Mitchell's Q-cycle. The overall rate of the intersystem electron transport is determined by PQH2 turnover at the quinone-binding site Qo of the Cyt b 6 f complex. The rate of PQH2 oxidation is controlled by the intrathylakoid pHin, which value determines the protonation/deprotonation events in the Qo-center. Two other regulatory mechanisms associated with the Cyt b 6 f complex are briefly overviewed: (i) redistribution of electron fluxes between alternative (linear and cyclic) pathways, and (ii) "state transitions" related to redistribution of solar energy between PSI and PSII.
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Dumas L, Zito F, Blangy S, Auroy P, Johnson X, Peltier G, Alric J. A stromal region of cytochrome b6f subunit IV is involved in the activation of the Stt7 kinase in Chlamydomonas. Proc Natl Acad Sci U S A 2017; 114:12063-12068. [PMID: 29078388 PMCID: PMC5692589 DOI: 10.1073/pnas.1713343114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The cytochrome (cyt) b6f complex and Stt7 kinase regulate the antenna sizes of photosystems I and II through state transitions, which are mediated by a reversible phosphorylation of light harvesting complexes II, depending on the redox state of the plastoquinone pool. When the pool is reduced, the cyt b6f activates the Stt7 kinase through a mechanism that is still poorly understood. After random mutagenesis of the chloroplast petD gene, coding for subunit IV of the cyt b6f complex, and complementation of a ΔpetD host strain by chloroplast transformation, we screened for impaired state transitions in vivo by chlorophyll fluorescence imaging. We show that residues Asn122, Tyr124, and Arg125 in the stromal loop linking helices F and G of cyt b6f subunit IV are crucial for state transitions. In vitro reconstitution experiments with purified cyt b6f and recombinant Stt7 kinase domain show that cyt b6f enhances Stt7 autophosphorylation and that the Arg125 residue is directly involved in this process. The peripheral stromal structure of the cyt b6f complex had, until now, no reported function. Evidence is now provided of a direct interaction with Stt7 on the stromal side of the membrane.
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Affiliation(s)
- Louis Dumas
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Aix-Marseille Université, UMR 7265, Institut de Biosciences et Biotechnologies d'Aix-Marseille, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France
| | - Francesca Zito
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, CNRS, UMR7099, University Paris Diderot, Sorbonne Paris Cité, Paris Sciences et Lettres Research University, F-75005 Paris, France
| | - Stéphanie Blangy
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Aix-Marseille Université, UMR 7265, Institut de Biosciences et Biotechnologies d'Aix-Marseille, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France
| | - Pascaline Auroy
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Aix-Marseille Université, UMR 7265, Institut de Biosciences et Biotechnologies d'Aix-Marseille, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France
| | - Xenie Johnson
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Aix-Marseille Université, UMR 7265, Institut de Biosciences et Biotechnologies d'Aix-Marseille, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France
| | - Gilles Peltier
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Aix-Marseille Université, UMR 7265, Institut de Biosciences et Biotechnologies d'Aix-Marseille, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France
| | - Jean Alric
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), CNRS, Aix-Marseille Université, UMR 7265, Institut de Biosciences et Biotechnologies d'Aix-Marseille, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France;
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Luján MA, Lorente P, Zazubovich V, Picorel R. A simple and efficient method to prepare pure dimers and monomers of the cytochrome b 6 f complex from spinach. PHOTOSYNTHESIS RESEARCH 2017; 132:305-309. [PMID: 28374305 DOI: 10.1007/s11120-017-0375-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/23/2017] [Indexed: 06/07/2023]
Abstract
Using a single size-exclusion chromatography we were able to isolate highly pure dimers and monomers of the Cyt b 6 f complex from spinach from a bulk preparation of that protein complex obtained with a standard procedure. At higher protein/detergent ratio during the chromatography most of the Cyt b 6 f complex remained as dimers. In contrast, at lower protein/detergent ratio (around 15 times lower), most dimers became monomerized. As a bonus, this chromatography also allowed the elimination of potential Chl a contaminant to the Cyt b 6 f preparations. SDS-PAGE protein analysis with 18% (w/v) acrylamide revealed the loss of the ISP subunit in our monomeric preparation. However, it fully retained the content of Chl a, a prerequisite to perform any spectroscopic study involving this unique pigment.
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Affiliation(s)
- María A Luján
- CSIC-Estación Experimental de Aula Dei, Avda. Montañana 1005, 50059, Zaragoza, Spain
| | - Patricia Lorente
- CSIC-Estación Experimental de Aula Dei, Avda. Montañana 1005, 50059, Zaragoza, Spain
| | - Valter Zazubovich
- Department of Physics, Concordia University, 7141 Sherbrook Str. West, Montreal, QC, H4B 1R6, Canada
| | - Rafael Picorel
- CSIC-Estación Experimental de Aula Dei, Avda. Montañana 1005, 50059, Zaragoza, Spain.
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14
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Chauvet AAP, Agarwal R, Haddad AA, van Mourik F, Cramer WA. Photo-induced oxidation of the uniquely liganded heme f in the cytochrome b6f complex of oxygenic photosynthesis. Phys Chem Chem Phys 2016; 18:12983-91. [PMID: 27108913 PMCID: PMC4990003 DOI: 10.1039/c6cp01592a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ultrafast behavior of the ferrous heme f from the cytochrome b6f complex of oxygenic photosynthesis is revealed by means of transient absorption spectroscopy. Benefiting from the use of microfluidic technologies for handling the sample as well as from a complementary frame-by-frame analysis of the heme dynamics, the different relaxation mechanisms from vibrationally excited states are disentangled and monitored via the shifts of the heme α-absorption band. Under 520 nm laser excitation, about 85% of the heme f undergoes pulse-limited photo-oxidation (<100 fs), with the electron acceptor being most probably one of the adjacent aromatic amino acid residues. After charge recombination in 5.3 ps, the residual excess energy is dissipated in 3.6 ps. In a parallel pathway, the remaining 15% of the hemes directly relax from their excited state in 2.5 ps. In contrast to a vast variety of heme-proteins, including the homologous heme c1 from the cytochrome bc1 complex, there is no evidence that heme f photo-dissociates from its axial ligands. Due to its unique binding, with histidine and an unusual tyrosine as axial ligands, the heme f exemplifies a dependence of ultrafast dynamics on the structural environment.
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Affiliation(s)
- Adrien A P Chauvet
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide (LSU), ISIC, Faculté des Sciences de Base and Lausanne Centre for Ultrafast Science (LACUS), Station 6, 1015 Lausanne, Switzerland.
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15
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Shapiguzov A, Chai X, Fucile G, Longoni P, Zhang L, Rochaix JD. Activation of the Stt7/STN7 Kinase through Dynamic Interactions with the Cytochrome b6f Complex. PLANT PHYSIOLOGY 2016; 171:82-92. [PMID: 26941194 PMCID: PMC4854690 DOI: 10.1104/pp.15.01893] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/02/2016] [Indexed: 05/20/2023]
Abstract
Photosynthetic organisms have the ability to adapt to changes in light quality by readjusting the cross sections of the light-harvesting systems of photosystem II (PSII) and photosystem I (PSI). This process, called state transitions, maintains the redox poise of the photosynthetic electron transfer chain and ensures a high photosynthetic yield when light is limiting. It is mediated by the Stt7/STN7 protein kinase, which is activated through the cytochrome b6f complex upon reduction of the plastoquinone pool. Its probable major substrate, the light-harvesting complex of PSII, once phosphorylated, dissociates from PSII and docks to PSI, thereby restoring the balance of absorbed light excitation energy between the two photosystems. Although the kinase is known to be inactivated under high-light intensities, the molecular mechanisms governing its regulation remain unknown. In this study we monitored the redox state of a conserved and essential Cys pair of the Stt7/STN7 kinase and show that it forms a disulfide bridge. We could not detect any change in the redox state of these Cys during state transitions and high-light treatment. It is only after prolonged anaerobiosis that this disulfide bridge is reduced. It is likely to be mainly intramolecular, although kinase activation may involve a transient covalently linked kinase dimer with two intermolecular disulfide bonds. Using the yeast two-hybrid system, we have mapped one interaction site of the kinase on the Rieske protein of the cytochrome b6f complex.
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Affiliation(s)
- Alexey Shapiguzov
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland (A.S.); and Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China (X.C., G.F., P.L., L.Z., J.-D.R.)
| | - Xin Chai
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland (A.S.); and Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China (X.C., G.F., P.L., L.Z., J.-D.R.)
| | - Geoffrey Fucile
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland (A.S.); and Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China (X.C., G.F., P.L., L.Z., J.-D.R.)
| | - Paolo Longoni
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland (A.S.); and Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China (X.C., G.F., P.L., L.Z., J.-D.R.)
| | - Lixin Zhang
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland (A.S.); and Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China (X.C., G.F., P.L., L.Z., J.-D.R.)
| | - Jean-David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland (A.S.); and Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China (X.C., G.F., P.L., L.Z., J.-D.R.)
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16
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The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part III. {[Fe2S2](Cys)3(X)} (X=Asp, Arg, His) and {[Fe2S2](Cys)2(His)2} proteins. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.07.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Structure-Function of the Cytochrome b 6 f Lipoprotein Complex. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2016. [DOI: 10.1007/978-94-017-7481-9_9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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18
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Hung CH, Endo K, Kobayashi K, Nakamura Y, Wada H. Characterization of Chlamydomonas reinhardtii phosphatidylglycerophosphate synthase in Synechocystis sp. PCC 6803. Front Microbiol 2015; 6:842. [PMID: 26379630 PMCID: PMC4547039 DOI: 10.3389/fmicb.2015.00842] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/31/2015] [Indexed: 12/22/2022] Open
Abstract
Phosphatidylglycerol (PG) is an indispensable phospholipid class with photosynthetic function in plants and cyanobacteria. However, its biosynthesis in eukaryotic green microalgae is poorly studied. Here, we report the isolation and characterization of two homologs (CrPGP1 and CrPGP2) of phosphatidylglycerophosphate synthase (PGPS), the rate-limiting enzyme in PG biosynthesis, in Chlamydomonas reinhardtii. Heterologous complementation of Synechocystis sp. PCC 6803 pgsA mutant by CrPGP1 and CrPGP2 rescued the PG-dependent growth phenotype, but the PG level and its fatty acid composition were not fully rescued in the complemented strains. As well, oxygen evolution activity was not fully recovered, although electron transport activity of photosystem II was restored to the wild-type level. Gene expression study of CrPGP1 and CrPGP2 in nutrient-starved C. reinhardtii showed differential response to phosphorus and nitrogen deficiency. Taken together, these results highlight the distinct and overlapping function of PGPS in cyanobacteria and eukaryotic algae.
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Affiliation(s)
- Chun-Hsien Hung
- Institute of Plant and Microbial Biology, Academia Sinica Taipei, Taiwan
| | - Kaichiro Endo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo Tokyo, Japan
| | - Koichi Kobayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo Tokyo, Japan
| | - Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia Sinica Taipei, Taiwan ; PRESTO, Japan Science and Technology Agency Saitama, Japan
| | - Hajime Wada
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo Tokyo, Japan ; CREST, Japan Science and Technology Agency Saitama, Japan
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19
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Vladkova R. Chlorophyllais the crucial redox sensor and transmembrane signal transmitter in the cytochromeb6fcomplex. Components and mechanisms of state transitions from the hydrophobic mismatch viewpoint. J Biomol Struct Dyn 2015; 34:824-54. [DOI: 10.1080/07391102.2015.1056551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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20
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Agarwal R, Hasan SS, Jones LM, Stofleth JT, Ryan CM, Whitelegge JP, Kehoe DM, Cramer WA. Role of domain swapping in the hetero-oligomeric cytochrome b6f lipoprotein complex. Biochemistry 2015; 54:3151-63. [PMID: 25928281 DOI: 10.1021/acs.biochem.5b00279] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Domain swapping that contributes to the stability of biologically crucial multisubunit complexes has been implicated in protein oligomerization. In the case of membrane protein assemblies, domain swapping of the iron-sulfur protein (ISP) subunit occurs in the hetero-oligomeric cytochrome b6f and bc1 complexes, which are organized as symmetric dimers that generate the transmembrane proton electrochemical gradient utilized for ATP synthesis. In these complexes, the ISP C-terminal predominantly β-sheet extrinsic domain containing the redox-active [2Fe-2S] cluster resides on the electrochemically positive side of each monomer in the dimeric complex. This domain is bound to the membrane sector of the complex through an N-terminal transmembrane α-helix that is "swapped' to the other monomer of the complex where it spans the complex and the membrane. Detailed analysis of the function and structure of the b6f complex isolated from the cyanobacterium Fremyella diplosiphon SF33 shows that the domain-swapped ISP structure is necessary for function but is not necessarily essential for maintenance of the dimeric structure of the complex. On the basis of crystal structures of the cytochrome complex, the stability of the cytochrome dimer is attributed to specific intermonomer protein-protein and protein-lipid hydrophobic interactions. The geometry of the domain-swapped ISP structure is proposed to be a consequence of the requirement that the anchoring helix of the ISP not perturb the heme organization or quinone channel in the conserved core of each monomer.
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Affiliation(s)
- Rachna Agarwal
- †Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - S Saif Hasan
- †Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - LaDonna M Jones
- ‡Department of Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - Jason T Stofleth
- †Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Christopher M Ryan
- §Pasarow Mass Spectrometry Laboratory, NPI-Semel Institute, University of California, Los Angeles, California 90095, United States
| | - Julian P Whitelegge
- §Pasarow Mass Spectrometry Laboratory, NPI-Semel Institute, University of California, Los Angeles, California 90095, United States
| | - David M Kehoe
- ‡Department of Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - William A Cramer
- †Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
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21
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Schöttler MA, Tóth SZ, Boulouis A, Kahlau S. Photosynthetic complex stoichiometry dynamics in higher plants: biogenesis, function, and turnover of ATP synthase and the cytochrome b6f complex. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2373-400. [PMID: 25540437 DOI: 10.1093/jxb/eru495] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
During plant development and in response to fluctuating environmental conditions, large changes in leaf assimilation capacity and in the metabolic consumption of ATP and NADPH produced by the photosynthetic apparatus can occur. To minimize cytotoxic side reactions, such as the production of reactive oxygen species, photosynthetic electron transport needs to be adjusted to the metabolic demand. The cytochrome b6f complex and chloroplast ATP synthase form the predominant sites of photosynthetic flux control. Accordingly, both respond strongly to changing environmental conditions and metabolic states. Usually, their contents are strictly co-regulated. Thereby, the capacity for proton influx into the lumen, which is controlled by electron flux through the cytochrome b6f complex, is balanced with proton efflux through ATP synthase, which drives ATP synthesis. We discuss the environmental, systemic, and metabolic signals triggering the stoichiometry adjustments of ATP synthase and the cytochrome b6f complex. The contribution of transcriptional and post-transcriptional regulation of subunit synthesis, and the importance of auxiliary proteins required for complex assembly in achieving the stoichiometry adjustments is described. Finally, current knowledge on the stability and turnover of both complexes is summarized.
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Affiliation(s)
- Mark Aurel Schöttler
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Szilvia Z Tóth
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Alix Boulouis
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Sabine Kahlau
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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22
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Tikhonov AN. The cytochrome b6f complex at the crossroad of photosynthetic electron transport pathways. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 81:163-83. [PMID: 24485217 DOI: 10.1016/j.plaphy.2013.12.011] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 12/11/2013] [Indexed: 05/03/2023]
Abstract
Regulation of photosynthetic electron transport at the level of the cytochrome b6f complex provides efficient performance of the chloroplast electron transport chain (ETC). In this review, after brief overview of the structural organization of the chloroplast ETC, the consideration of the problem of electron transport control is focused on the plastoquinone (PQ) turnover and its interaction with the b6f complex. The data available show that the rates of plastoquinol (PQH2) formation in PSII and its diffusion to the b6f complex do not limit the overall rate of electron transfer between photosystem II (PSII) and photosystem I (PSI). Analysis of experimental and theoretical data demonstrates that the rate-limiting step in the intersystem chain of electron transport is determined by PQH2 oxidation at the Qo-site of the b6f complex, which is accompanied by the proton release into the thylakoid lumen. The acidification of the lumen causes deceleration of PQH2 oxidation, thus impeding the intersystem electron transport. Two other mechanisms of regulation of the intersystem electron transport have been considered: (i) "state transitions" associated with the light-induced redistribution of solar energy between PSI and PSII, and (ii) redistribution of electron fluxes between alternative pathways (noncyclic electron transport and cyclic electron flow around PSI).
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23
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Hojka M, Thiele W, Tóth SZ, Lein W, Bock R, Schöttler MA. Inducible Repression of Nuclear-Encoded Subunits of the Cytochrome b6f Complex in Tobacco Reveals an Extraordinarily Long Lifetime of the Complex. PLANT PHYSIOLOGY 2014; 165:1632-1646. [PMID: 24963068 PMCID: PMC4119044 DOI: 10.1104/pp.114.243741] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 06/24/2014] [Indexed: 05/18/2023]
Abstract
The biogenesis of the cytochrome b6f complex in tobacco (Nicotiana tabacum) seems to be restricted to young leaves, suggesting a high lifetime of the complex. To directly determine its lifetime, we employed an ethanol-inducible RNA interference (RNAi) approach targeted against the essential nuclear-encoded Rieske protein (PetC) and the small M subunit (PetM), whose function in higher plants is unknown. Young expanding leaves of both PetM and PetC RNAi transformants bleached rapidly and developed necroses, while mature leaves, whose photosynthetic apparatus was fully assembled before RNAi induction, stayed green. In line with these phenotypes, cytochrome b6f complex accumulation and linear electron transport capacity were strongly repressed in young leaves of both RNAi transformants, showing that the M subunit is as essential for cytochrome b6f complex accumulation as the Rieske protein. In mature leaves, all photosynthetic parameters were indistinguishable from the wild type even after 14 d of induction. As RNAi repression of PetM and PetC was highly efficient in both young and mature leaves, these data indicate a lifetime of the cytochrome b6f complex of at least 1 week. The switch-off of cytochrome b6f complex biogenesis in mature leaves may represent part of the first dedicated step of the leaf senescence program.
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Affiliation(s)
- Marta Hojka
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Wolfram Thiele
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Szilvia Z Tóth
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Wolfgang Lein
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Mark Aurel Schöttler
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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24
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Internal lipid architecture of the hetero-oligomeric cytochrome b6f complex. Structure 2014; 22:1008-15. [PMID: 24931468 DOI: 10.1016/j.str.2014.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/04/2014] [Accepted: 05/06/2014] [Indexed: 12/18/2022]
Abstract
The role of lipids in the assembly, structure, and function of hetero-oligomeric membrane protein complexes is poorly understood. The dimeric photosynthetic cytochrome b6f complex, a 16-mer of eight distinct subunits and 26 transmembrane helices, catalyzes transmembrane proton-coupled electron transfer for energy storage. Using a 2.5 Å crystal structure of the dimeric complex, we identified 23 distinct lipid-binding sites per monomer. Annular lipids are proposed to provide a connection for super-complex formation with the photosystem-I reaction center and the LHCII kinase enzyme for transmembrane signaling. Internal lipids mediate crosslinking to stabilize the domain-swapped iron-sulfur protein subunit, dielectric heterogeneity within intermonomer and intramonomer electron transfer pathways, and dimer stabilization through lipid-mediated intermonomer interactions. This study provides a complete structure analysis of lipid-mediated functions in a multi-subunit membrane protein complex and reveals lipid sites at positions essential for assembly and function.
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25
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An F, Fan J, Li J, Li QX, Li K, Zhu W, Wen F, Carvalho LJCB, Chen S. Comparison of leaf proteomes of cassava (Manihot esculenta Crantz) cultivar NZ199 diploid and autotetraploid genotypes. PLoS One 2014; 9:e85991. [PMID: 24727655 PMCID: PMC3984080 DOI: 10.1371/journal.pone.0085991] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 12/03/2013] [Indexed: 12/27/2022] Open
Abstract
Cassava polyploid breeding has drastically improved our knowledge on increasing root yield and its significant tolerance to stresses. In polyploid cassava plants, increases in DNA content highly affect cell volumes and anatomical structures. However, the mechanism of this effect is poorly understood. The purpose of the present study was to compare and validate the changes between cassava cultivar NZ199 diploid and autotetraploid at proteomic levels. The results showed that leaf proteome of cassava cultivar NZ199 diploid was clearly differentiated from its autotetraploid genotype using 2-DE combined MS technique. Sixty-five differential protein spots were seen in 2-DE image of autotetraploid genotype in comparison with that of diploid. Fifty-two proteins were identified by MALDI-TOF-MS/MS, of which 47 were up-regulated and 5 were down-regulated in autotetraploid genotype compared with diploid genotype. The classified functions of 32 up-regulated proteins were associated with photosynthesis, defense system, hydrocyanic acid (HCN) metabolism, protein biosynthesis, chaperones, amino acid metabolism and signal transduction. The remarkable variation in photosynthetic activity, HCN content and resistance to salt stress between diploid and autotetraploid genotypes is closely linked with expression levels of proteomic profiles. The analysis of protein interaction networks indicated there are direct interactions between the 15 up-regulation proteins involved in the pathways described above. This work provides an insight into understanding the protein regulation mechanism of cassava polyploid genotype, and gives a clue to improve cassava polyploidy breeding in increasing photosynthesis and resistance efficiencies.
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Affiliation(s)
- Feifei An
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Ministry of Agriculture for Germplasm Resources Conservation and Utilization of Cassava, Hainan, China
| | - Jie Fan
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Ministry of Agriculture for Germplasm Resources Conservation and Utilization of Cassava, Hainan, China
| | - Jun Li
- Analysis and Testing Center, Jiangsu University, Jiangsu, China
| | - Qing X. Li
- Proteomics Core Facility, Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Manoa, Hawaii, United States of America
| | - Kaimian Li
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Ministry of Agriculture for Germplasm Resources Conservation and Utilization of Cassava, Hainan, China
- * E-mail: (KL); (SC)
| | - Wenli Zhu
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Ministry of Agriculture for Germplasm Resources Conservation and Utilization of Cassava, Hainan, China
| | - Feng Wen
- Guangxi Sub-tropical Crop Research Institute, Nanning, China
| | | | - Songbi Chen
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Ministry of Agriculture for Germplasm Resources Conservation and Utilization of Cassava, Hainan, China
- * E-mail: (KL); (SC)
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