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Zabelin AA, Khristin AM, Kovalev VB, Khatypov RA, Shkuropatov AY. Primary charge separation in native and plant pheophytin a-modified reaction centers of Chloroflexus aurantiacus: Ultrafast transient absorption measurements at low temperature. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148976. [PMID: 37061174 DOI: 10.1016/j.bbabio.2023.148976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/31/2023] [Accepted: 04/06/2023] [Indexed: 04/17/2023]
Abstract
Ultrafast transient absorption (TA) spectroscopy was used to study electron transfer (ET) at 100 K in native (as isolated) reaction centers (RCs) of the green filamentous photosynthetic bacterium Chloroflexus (Cfl.) aurantiacus. The rise and decay of the 1028 nm anion absorption band of the monomeric bacteriochlorophyll a molecule at the BA binding site were monitored as indicators of the formation and decay of the P+BA- state, respectively (P is the primary electron donor, a dimer of bacteriochlorophyll a molecules). Global analysis of the TA data indicated the presence of at least two populations of the P⁎ excited state, which decay by distinct means, forming the state P+HA- (HA is a photochemically active bacteriopheophytin a molecule). In one population (~65 %), P⁎ decays in ~2 ps with the formation of P+HA- via a short-lived P+BA- intermediate in a two-step ET process P⁎ → P+BA- → P+HA-. In another population (~35 %), P⁎ decays in ~20 ps to form P+HA- via a superexchange mechanism without producing measurable amounts of P+BA-. Similar TA measurements performed on chemically modified RCs of Cfl. aurantiacus containing plant pheophytin a at the HA binding site also showed the presence of two P⁎ populations (~2 and ~20 ps), with P⁎ decaying through P+BA- only in the ~2 ps population. At 100 K, the quantum yield of primary charge separation in native RCs is determined to be close to unity. The results are discussed in terms of involving a one-step P⁎ → P+HA- superexchange process as an alternative highly efficient ET pathway in Cfl. aurantiacus RCs.
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Affiliation(s)
- Alexey A Zabelin
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Anton M Khristin
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Vyacheslav B Kovalev
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Ravil A Khatypov
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Anatoly Yu Shkuropatov
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation.
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Kim J, Lee JK, Kim EJ. Chlorophyll a Synthesis in Rhodobacter sphaeroides by Chlorophyll Synthase of Nicotiana tabacum. BIOLOGY 2023; 12:biology12040573. [PMID: 37106772 PMCID: PMC10136183 DOI: 10.3390/biology12040573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/05/2023] [Accepted: 04/08/2023] [Indexed: 04/29/2023]
Abstract
The production of phytylated chlorophyll a (Chl aP) in Rhodobacter sphaeroides, which uses phytylated bacteriochlorophyll a (BChl aP), is the first step in expanding the light absorption spectra. Unlike the chlorophyll synthase (ChlG) of the Synechocystis sp. PCC6803, ChlGs of angiosperms, including Arabidopsis thaliana, Nicotiana tabacum, Avena sativa, and Oryza sativa, showed bacteriochlorophyll synthase activity and resistance to inhibition by bacteriochlorophyllide a (BChlide a), geranylgeranylated BChl a (BChl aGG), and BChl aP, collectively called bacteriochlorins. Among the angiosperm ChlGs, N. tabacum ChlG had the highest bacteriochlorophyll synthase activity and resistance to inhibition by bacteriochlorins. Expression of N. tabacum chlG in R. sphaeroides resulted in the formation of free Chl aP in the presence of BChl aP during photoheterotrophic growth, even though reactive oxygen species were generated.
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Affiliation(s)
- June Kim
- Department of Life Science, Sogang University, Seoul 04107, Republic of Korea
| | - Jeong K Lee
- Department of Life Science, Sogang University, Seoul 04107, Republic of Korea
| | - Eui-Jin Kim
- Microbial Research Department, Nakdonggang National Institute of Biological Resources, Sangju 37242, Republic of Korea
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Kim J, Kim C, Kim S, Ihee H, Shin W, Kim EJ, Lee JK. The Photoactive Photosynthetic Reaction Center of a Rhodobacter sphaeroides Mutant Lacking 3-Vinyl (Bacterio)Chlorophyllide a Hydratase Contains 3-Vinyl Bacteriochlorophyll a. Microbiol Spectr 2023; 11:e0387822. [PMID: 36971575 PMCID: PMC10101016 DOI: 10.1128/spectrum.03878-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 02/20/2023] [Indexed: 03/29/2023] Open
Abstract
Rhodobacter sphaeroides mutant BF-lacking 3-vinyl (bacterio)chlorophyllide a hydratase (BchF)-accumulates chlorophyllide a (Chlide a) and 3-vinyl bacteriochlorophyllide a (3V-Bchlide a). BF synthesizes 3-vinyl bacteriochlorophyll a (3V-Bchl a) through prenylation of 3V-Bchlide a and assembles a novel reaction center (V-RC) using 3V-Bchl a and Mg-free 3-vinyl bacteriopheophytin a (3V-Bpheo a) at a molar ratio of 2:1. We aimed to verify whether a bchF-deleted R. sphaeroides mutant produces a photochemically active RC that facilitates photoheterotrophic growth. The mutant grew photoheterotrophically-implying a functional V-RC-as confirmed by the emergence of growth-competent suppressors of bchC-deleted mutant (BC) under irradiation. Suppressor mutations in BC were localized to bchF, which diminished BchF activity and caused 3V-Bchlide a accumulation. bchF expression carrying the suppressor mutations in trans resulted in the coproduction of V-RC and wild-type RC (WT-RC) in BF. The V-RC had a time constant (τ) for electron transfer from the primary electron donor P (a dimer of 3V-Bchl a) to the A-side containing 3V-Bpheo a (HA) similar to that of the WT-RC and a 60% higher τ for electron transfer from HA to quinone A (QA). Thus, the electron transfer from HA to QA in the V-RC should be slower than that in the WT-RC. Furthermore, the midpoint redox potential of P/P+ of the V-RC was 33 mV more positive than that of the WT-RC. R. sphaeroides, thus, synthesizes the V-RC when 3V-Bchlide a accumulates. The V-RC can support photoheterotrophic growth; however, its photochemical activity is inferior to that of the WT-RC. IMPORTANCE 3V-Bchlide a is an intermediate in the bacteriochlorophyll a (Bchl a)-specific biosynthetic branch and prenylated by bacteriochlorophyll synthase. R. sphaeroides synthesizes V-RC that absorbs light at short wavelengths. The V-RC was not previously discovered because 3V-Bchlide a does not accumulate during the growth of WT cells synthesizing Bchl a. The levels of reactive oxygen species increased with the onset of photoheterotrophic growth in BF, resulting in a long lag period. Although the inhibitor of BchF is unknown, the V-RC may act as a substitute for the WT-RC when BchF is completely inhibited. Alternatively, it may act synergistically with WT-RC at low levels of BchF activity. The V-RC may broaden the absorption spectra of R. sphaeroides and supplement its photosynthetic ability at various wavelengths of visible light to a greater extent than that by the WT-RC alone.
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Affiliation(s)
- June Kim
- Department of Life Science, Sogang University, Seoul, Republic of Korea
| | - Changwon Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science, Daejeon, Republic of Korea
| | - Siin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science, Daejeon, Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science, Daejeon, Republic of Korea
| | - Woonsup Shin
- Department of Chemistry, Sogang University, Seoul, Republic of Korea
| | - Eui-Jin Kim
- Microbial Research Department, Nakdonggang National Institute of Biological Resources, Gyeongsangbuk-do, Republic of Korea
| | - Jeong K. Lee
- Department of Life Science, Sogang University, Seoul, Republic of Korea
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Zabelin AA, Shkuropatov AY. Pigment-modified reaction centers of Chloroflexus aurantiacus: chemical exchange of bacteriopheophytins with plant-type pheophytins. PHOTOSYNTHESIS RESEARCH 2021; 149:313-328. [PMID: 34138452 DOI: 10.1007/s11120-021-00855-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/06/2021] [Indexed: 06/12/2023]
Abstract
The pigment composition of isolated reaction centers (RCs) of the green filamentous bacterium Chloroflexus (Cfl.) aurantiacus was changed by chemical exchange of native bacteriopheophytin a (BPheo) molecules with externally added pheophytin a (Pheo) or [3-acetyl]-Pheo upon incubation of RC/pheophytin mixtures at room temperature and 45 °C. The modified RCs were characterized by Vis/NIR absorption spectroscopy, and the effect of pigment exchange on RC photochemical activity was assessed by measuring the photoaccumulation of the reduced pigment at the binding site HA. It is shown that both pheophytins can be exchanged into the HA site instead of BPheo by incubation at room temperature. While the newly introduced Pheo molecule is not active in electron transfer, the [3-acetyl]-Pheo molecule is able to replace functionally the photoreducible HA BPheo molecule with the formation of the [3-acetyl]-Pheo- radical anion instead of the BPheo-. After incubation at 45 °C, the majority (~ 90%) of HA BPheo molecules is replaced by both Pheo and [3-acetyl]-Pheo. Only a partial replacement of inactive BPheo molecules with pheophytins is observed even when the incubation temperature is raised to 50 °C. The results are discussed in terms of (i) differences in the accessibility of BPheo binding sites for extraneous pigments depending on structural constraints and incubation temperature and (ii) the effect of the reduction potential of pigments introduced into the HA site on the energetics of the charge separation process. The possible implication of Pheo-exchanged preparations for studying early electron-transfer events in Cfl. aurantiacus RCs is considered.
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Affiliation(s)
- Alexey A Zabelin
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Basic Biological Problems of the Russian Academy of Sciences, 142290, Pushchino, Moscow Region, Russian Federation
| | - Anatoly Ya Shkuropatov
- Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Basic Biological Problems of the Russian Academy of Sciences, 142290, Pushchino, Moscow Region, Russian Federation.
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Magdaong NCM, Buhrmaster JC, Faries KM, Liu H, Tira GA, Lindsey JS, Hanson DK, Holten D, Laible PD, Kirmaier C. In Situ, Protein-Mediated Generation of a Photochemically Active Chlorophyll Analogue in a Mutant Bacterial Photosynthetic Reaction Center. Biochemistry 2021; 60:1260-1275. [PMID: 33835797 DOI: 10.1021/acs.biochem.1c00137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
All possible natural amino acids have been substituted for the native LeuL185 positioned near the B-side bacteriopheophytin (HB) in the bacterial reaction center (RC) from Rhodobacter sphaeroides. Additional mutations that enhance electron transfer to the normally inactive B-side cofactors are present. Approximately half of the isolated RCs with Glu at L185 contain a magnesium chlorin (CB) in place of HB. The chlorin is not the common BChl a oxidation product 3-desvinyl-3-acetyl chlorophyll a with a C-C bond in ring D and a C═C bond in ring B but has properties consistent with reversal of these bond orders, giving 17,18-didehydro BChl a. In such RCs, charge-separated state P+CB- forms in ∼5% yield. The other half of the GluL185-containing RCs have a bacteriochlorophyll a (BChl a) denoted βB in place of HB. Residues His, Asp, Asn, and Gln at L185 yield RCs with ≥85% βB in the HB site, while most other amino acids result in RCs that retain HB (≥95%). To the best of our knowledge, neither bacterial RCs that harbor five BChl a molecules and one chlorophyll analogue nor those with six BChl a molecules have been reported previously. The finding that altering the local environment within a cofactor binding site of a transmembrane complex leads to in situ generation of a photoactive chlorin with an unusual ring oxidation pattern suggests new strategies for amino acid control over pigment type at specific sites in photosynthetic proteins.
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Affiliation(s)
- Nikki Cecil M Magdaong
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - James C Buhrmaster
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kaitlyn M Faries
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Haijun Liu
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Gregory A Tira
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Jonathan S Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Deborah K Hanson
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Dewey Holten
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Philip D Laible
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Christine Kirmaier
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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Pan J, Saer R, Lin S, Beatty JT, Woodbury NW. Electron Transfer in Bacterial Reaction Centers with the Photoactive Bacteriopheophytin Replaced by a Bacteriochlorophyll through Coordinating Ligand Substitution. Biochemistry 2016; 55:4909-18. [DOI: 10.1021/acs.biochem.6b00317] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jie Pan
- The
Biodesign Institute at Arizona State University, Arizona State University, Tempe, Arizona 85287-5201, United States
| | - Rafael Saer
- Department
of Microbiology and Immunology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Su Lin
- The
Biodesign Institute at Arizona State University, Arizona State University, Tempe, Arizona 85287-5201, United States
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - J. Thomas Beatty
- Department
of Microbiology and Immunology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Neal W. Woodbury
- The
Biodesign Institute at Arizona State University, Arizona State University, Tempe, Arizona 85287-5201, United States
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
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Yakovlev AG, Shuvalov VA. Modeling of reversible charge separation in reaction centers of photosynthesis: an incoherent approach. J Theor Biol 2014; 343:92-101. [PMID: 24270095 DOI: 10.1016/j.jtbi.2013.11.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/28/2013] [Accepted: 11/13/2013] [Indexed: 10/26/2022]
Abstract
Primary charge separation in reaction centers (RCs) of bacterial photosynthesis is modeled in this work. An incoherent population dynamics of RCs states is formulated by kinetic equations. It is assumed that charge separation is accompanied by regular motion of the system along additional coordinates. This motion modulates an energetics of the reactions, and this modulation causes femtosecond oscillations in the population of the states. The best qualitative and quantitative accordance with experimental data on native, modified and mutant RCs of Rba. sphaeroides is achieved in the five states model that includes two excited states P(*)905BAHA and P(*)940BAHA and three charge separated states I, P(+)BA(-)HA and P(+)BAHA(-) (P is a primary electron donor, bacteriochlorophyll dimer, BA and HA are electron acceptors, monomeric bacteriochlorophyll and bacteriopheophytin in active A-branch respectively). The excited states emit at 905 and 940 nm and have approximately the same energy and high interaction rate. The intermediate state I is populated earlier than the P(+)BA(-)HA state and has energy close to the energy of the excited states, a high rate of population and depopulation and spectral identity to the BA(-). A sum of the I and P(+)BA(-)HA populations fits the experimental kinetics of the BA(-) absorption band at 1020 nm. The model explains an oscillatory phenomenon in the kinetics of the P(*) stimulated emission and of the BA(-) absorption. In the schemes without the I state, accordance with the experiment is achieved at unreal parameter values or is not achieved at all. A qualitative agreement of the model with the experiment can be achieved at a wide range of parameter values. The nature of the states I and P(*)940BAHA is discussed in terms of partial charge separation between P and BA and inside P respectively.
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Affiliation(s)
- A G Yakovlev
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskie Gory, 119991 Moscow, Russia.
| | - V A Shuvalov
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskie Gory, 119991 Moscow, Russia; Institute of Basic Biological Problems, Russian Academy of Sciences, 142290 Pushchino, Moscow region, Russia.
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Yakovlev AG, Shuvalov VA. Formation of Bacteriochlorophyll Anion Band at 1020 nm Produced by Nuclear Wavepacket Motion in Bacterial Reaction Centers. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200000097] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Sai Sankar Gupta KB, Alia A, Buda F, de Groot HJM, Matysik J. Bacteriopheophytin a in the active branch of the reaction center of rhodobacter sphaeroides is not disturbed by the protein matrix as shown by 13C photo-CIDNP MAS NMR. J Phys Chem B 2013; 117:3287-97. [PMID: 23452037 DOI: 10.1021/jp3121319] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structure of bacteriopheophytin a (BPhe a), the primary electron acceptor (ΦA) in photosynthetic reaction centers (RCs) of the purple bacterium Rhodobacter sphaeroides, is investigated by photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) NMR spectroscopy at atomic resolution. By using various isotope labeling systems, introduced by adding different (13)C selectively labeled δ-aminolevulinic acid precursors in the growing medium of R. sphaeroides wild type (WT), we were able to extract light-induced (13)C NMR signals originating from the primary electron acceptor. The assignments are backed by theoretical calculations. By comparison of these chemical shifts to those obtained from monomeric BPhe a in solution, it is demonstrated that ΦA in the active branch appears to be electronically close to free bacteriopheophytin. Hence, there is little effect of the protein surrounding on the cofactor functionally which contributes with its standard redox potential to the electron transfer process that is asymmetric.
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Leonova MM, Fufina TY, Vasilieva LG, Shuvalov VA. Structure-function investigations of bacterial photosynthetic reaction centers. BIOCHEMISTRY (MOSCOW) 2012; 76:1465-83. [DOI: 10.1134/s0006297911130074] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Jones MR. Structural Plasticity of Reaction Centers from Purple Bacteria. THE PURPLE PHOTOTROPHIC BACTERIA 2009. [DOI: 10.1007/978-1-4020-8815-5_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Xu J, Lu Y, Liu B, Xu C, Kong J. Sensitively probing the cofactor redox species and photo-induced electron transfer of wild-type and pheophytin-replaced photosynthetic proteins reconstituted in self-assembled monolayers. J Solid State Electrochem 2007. [DOI: 10.1007/s10008-007-0330-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Klenina I, Borovykh I, Shkuropatov A, Gast P, Proskuryakov I. Orientation of the Qy optical transition moment of bacteriopheophytin in Rhodobacter sphaeroides reaction centers. Chem Phys 2003. [DOI: 10.1016/s0301-0104(03)00325-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Shuvalov VA, Yakovlev AG. Coupling of nuclear wavepacket motion and charge separation in bacterial reaction centers. FEBS Lett 2003; 540:26-34. [PMID: 12681478 DOI: 10.1016/s0014-5793(03)00237-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The mechanism of the charge separation and stabilization of separated charges was studied using the femtosecond absorption spectroscopy. It was found that nuclear wavepacket motions on potential energy surface of the excited state of the primary electron donor P* leads to a coherent formation of the charge separated states P(+)B(A)(-), P(+)H(A)(-) and P(+)H(B)(-) (where B(A), H(B) and H(A) are the primary and secondary electron acceptors, respectively) in native, pheophytin-modified and mutant reaction centers (RCs) of Rhodobacter sphaeroides R-26 and in Chloroflexus aurantiacus RCs. The processes were studied by measurements of coherent oscillations in kinetics at 890 and 935 nm (the stimulated emission bands of P*), at 800 nm (the absorption band of B(A)) and at 1020 nm (the absorption band of B(A)(-)) as well as at 760 nm (the absorption band of H(A)) and at 750 nm (the absorption band of H(B)). It was found that wavepacket motion on the 130-150 cm(-1) potential surface of P* is accompanied by approaches to the intercrossing region between P* and P(+)B(A)(-) surfaces at 120 and 380 fs delays emitting light at 935 nm (P*) and absorbing light at 1020 nm (P(+)B(A)(-)). In the presence of Tyr M210 (Rb. sphaeroides) or M195 (C. aurantiacus) the stabilization of P(+)B(A)(-) is observed within a few picosseconds in contrast to YM210W. At even earlier delay (approximately 40 fs) the emission at 895 nm and bleaching at 748 nm are observed in C. aurantiacus RCs showing the wavepacket approach to the intercrossing between the P* and P(+)H(B)(-) surfaces at that time. The 32 cm(-1) rotation mode of HOH was found to modulate the electron transfer rate probably due to including of this molecule in polar chain connecting P(B) and B(A) and participating in the charge separation. The mechanism of the charge separation and stabilization of separated charges is discussed in terms of the role of nuclear motions, of polar groups connecting P and acceptors and of proton of OH group of TyrM210.
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Affiliation(s)
- V A Shuvalov
- Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology of Moscow State University, Moscow 119992, Russia.
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Shkuropatov AY, Neerken S, Permentier HP, de Wijn R, Schmidt KA, Shuvalov VA, Aartsma TJ, Gast P, Hoff AJ. The effect of exchange of bacteriopheophytin a with plant pheophytin a on charge separation in Y(M210)W mutant reaction centers of Rhodobacter sphaeroides at low temperature. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1557:1-12. [PMID: 12615343 DOI: 10.1016/s0005-2728(02)00373-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The bacteriopheophytin a molecules at the H(A) and H(B) binding sites of reaction centers (RCs) of the Y(M210)W mutant of Rhodobacter sphaeroides were chemically exchanged with plant pheophytin a. The Y(M210)W mutation slows down the formation of H(A)(-), presumably by raising the free energy level of the P(+)B(A)(-) state above that of P* due to increasing the oxidation potential of the primary electron donor P and lowering the reduction potential of the accessory bacteriochlorophyll B(A). Exchange of the bacteriopheophytins with pheophytin a on the contrary lowers the redox potential of H(A), inhibiting its reduction. A combination of the mutation and pigment exchange was therefore expected to make the A-side of the RC incapable of electron transfer and cause the excited state P* to deactivate directly to the ground state or through the B-side, or both. Time-resolved absorption difference spectroscopy at 10 K on the RCs that were modified in this way showed a lifetime of P* lengthened to about 500 ps as compared to about 200 ps measured in the original Y(M210)W RCs. We show that the decay of P* in the pheophytin-exchanged preparations is accompanied by both return to the ground state and formation of a new charge-separated state, the absorption difference spectrum of which is characterized by bleachings at 811 and 890 nm. This latter state was formed with a time constant of ca. 1.7 ns and a yield of about 30%, and lasted a few nanoseconds. On the basis of spectroscopic observations these bands at 811 and 890 nm are tentatively attributed to the presence of the P(+)B(B)(-) state, where B(B) is the accessory bacteriochlorophyll in the "inactive" B-branch of the cofactors. The B(B) molecules in Y(M210)W RCs are suggested to be spectrally heterogeneous, absorbing in the Q(y) region at 813 or 806 nm. The results are discussed in terms of perturbation of the free energy level of the P(+)B(B)(-) state and absorption properties of the B(B) bacteriochlorophyll in the mutant RCs due to a long-range effect of the Y(M210)W mutation on the protein environment of the B(B) binding pocket.
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Affiliation(s)
- Anatoli Ya Shkuropatov
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russian Federation.
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Schenkl S, Spörlein S, Müh F, Witt H, Lubitz W, Zinth W, Wachtveitl J. Selective perturbation of the second electron transfer step in mutant bacterial reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1554:36-47. [PMID: 12034469 DOI: 10.1016/s0005-2728(02)00211-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to specifically perturb the primary electron acceptor B(A) -- a monomeric bacteriochlorophyll (BChl) a -- involved in bacterial photosynthetic charge separation (CS), the protein environment of B(A) in the reaction center (RC) of Rhodobacter sphaeroides was modified by site-directed mutagenesis. Isolated RCs were characterized by redox titrations, low temperature optical spectroscopy, ENDOR/TRIPLE resonance spectroscopy and femtosecond time-resolved spectroscopy. Two mutations were studied: In the GS(M203) mutant a serine is introduced near the ring E keto group of B(A), while in FY(L146) a phenylalanine near the ring A acetyl group of B(A) is replaced by tyrosine. In all mutations the oxidation potential of the primary electron donor P as well as the electronic structure of both the P(*+) radical cation and the radical anion of the secondary electron acceptor, H(A)(*-), are not significantly altered compared to the wild type (WT), while changes of the optical absorption spectra at 77 K in the BChl Q(X) and Q(Y) regions are observed. The GS(M203) mutation only leads to a minor retardation of the CS reactions at room temperature, whereas for FY(L146) significant deviations from the native electron transfer (ET) rates could be detected: In addition to a faster first (2.9 ps) and a slower second (1 ps) ET step, a new 8-ps time constant was found in the FY(L146) mutant, which can be ascribed to a fraction of RCs with slowed down secondary ET. The results allow us to address the functional role of the acetyl group of B(A) and question the role of the free energy changes as the main determining factor of ET rates in RCs. It is concluded that structural rearrangements alter the electronic coupling between the pigments and thereby influence the rate of fast CS.
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Affiliation(s)
- Selma Schenkl
- Sektion Physik, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany
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Spörlein S, Zinth W, Meyer M, Scheer H, Wachtveitl J. Primary electron transfer in modified bacterial reaction centers: optimization of the first events in photosynthesis. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)00471-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Yakovlev AG, Shkuropatov AY, Shuvalov VA. Nuclear wavepacket motion producing a reversible charge separation in bacterial reaction centers. FEBS Lett 2000; 466:209-12. [PMID: 10682829 DOI: 10.1016/s0014-5793(00)01081-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The excitation of bacterial reaction centers (RCs) at 870 nm by 30 fs pulses induces the nuclear wavepacket motions on the potential energy surface of the primary electron donor excited state P*, which lead to the fs oscillations in stimulated emission from P* [M.H. Vos, M.R. Jones, C.N. Hunter, J. Breton, J.-C. Lambry and J.-L. Martin (1994) Biochemistry 33, 6750-6757] and in Qy absorption band of the primary electron acceptor, bacteriochlorophyll monomer B(A) [A.M. Streltsov, S.I.E. Vulto, A.Y. Shkuropatov, A.J. Hoff, T.J. Aartsma and V.A. Shuvalov (1998) J. Phys. Chem. B 102, 7293-7298] with a set of fundamental frequencies in the range of 10-300 cm(-1). We have found that in pheophytin-modified RCs, the fs oscillations with frequency around 130 cm(-1) observed in the P*-stimulated emission as well as in the B(A) absorption band at 800 nm are accompanied by remarkable and reversible formation of the 1020 nm absorption band which is characteristic of the radical anion band of bacteriochlorophyll monomer B(A)-. These results are discussed in terms of a reversible electron transfer between P* and B(A) induced by a motion of the wavepacket near the intersection of potential energy surfaces of P* and P+B(A)-, when a maximal value of the Franck-Condon factor is created.
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Affiliation(s)
- A G Yakovlev
- Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology of Moscow State University, Russia
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Ogrodnik A, Hartwich G, Lossau H, Michel-Beyerle M. Dispersive charge separation and conformational cooling of P+HA− in reaction centers of Rb. sphaeroides R26: a spontaneous emission study. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00037-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Vulto SIE, de Baat MA, Louwe RJW, Permentier HP, Neef T, Miller M, van Amerongen H, Aartsma TJ. Exciton Simulations of Optical Spectra of the FMO Complex from the Green Sulfur Bacterium Chlorobium tepidum at 6 K. J Phys Chem B 1998. [DOI: 10.1021/jp982095l] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simone I. E. Vulto
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Michiel A. de Baat
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Robert J. W. Louwe
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Hjalmar P. Permentier
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Tatjana Neef
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Mette Miller
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Herbert van Amerongen
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Thijs J. Aartsma
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands; Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark; and Biophysics Department, Free University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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Streltsov AM, Vulto SIE, Shkuropatov AY, Hoff AJ, Aartsma TJ, Shuvalov VA. BA and BB Absorbance Perturbations Induced by Coherent Nuclear Motions in Reaction Centers from Rhodobacter sphaeroides upon 30-fs Excitation of the Primary Donor. J Phys Chem B 1998. [DOI: 10.1021/jp981514b] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. M. Streltsov
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands, Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology, Moscow State University, Moscow, 119899 Russia, and Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushino, Moscow regoin, 142292, Russia
| | - S. I. E. Vulto
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands, Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology, Moscow State University, Moscow, 119899 Russia, and Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushino, Moscow regoin, 142292, Russia
| | - A. Ya. Shkuropatov
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands, Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology, Moscow State University, Moscow, 119899 Russia, and Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushino, Moscow regoin, 142292, Russia
| | - A. J. Hoff
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands, Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology, Moscow State University, Moscow, 119899 Russia, and Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushino, Moscow regoin, 142292, Russia
| | - T. J. Aartsma
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands, Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology, Moscow State University, Moscow, 119899 Russia, and Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushino, Moscow regoin, 142292, Russia
| | - V. A. Shuvalov
- Biophysics Department, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands, Laboratory of Photobiophysics, Belozersky Institute of Chemical and Physical Biology, Moscow State University, Moscow, 119899 Russia, and Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushino, Moscow regoin, 142292, Russia
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Kennis JT, Shkuropatov AY, van Stokkum IH, Gast P, Hoff AJ, Shuvalov VA, Aartsma TJ. Formation of a long-lived P+BA- state in plant pheophytin-exchanged reaction centers of Rhodobacter sphaeroides R26 at low temperature. Biochemistry 1997; 36:16231-8. [PMID: 9405057 DOI: 10.1021/bi9712605] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Femtosecond transient absorption spectroscopy in the range of 500-1040 nm was used to study electron transfer at 5 K in reaction centers of Rhodobacter sphaeroides R26 in which the bacteriopheophytins (BPhe) were replaced by plant pheophytin a (Phe). Primary charge separation took place with a time constant of 1.6 ps, similar to that found in native RCs. Spectral changes around 1020 nm indicated the formation of reduced bacteriochlorophyll (BChl) with the same time constant, and its subsequent decay in 620 ps. This observation identifies the accessory BChl as the primary electron acceptor. No evidence was found for electron transfer to Phe, indicating that electron transfer from BA- occurs directly to the quinone (QA) through superexchange. The results are explained by a model in which the free energy level of P+Phe- lies above that of P+BA-, which itself is below P*. Assuming that the pigment exchange does not affect the energy levels of P* and P+BA-, our results strongly support a two-step model for primary electron transfer in the native bacterial RC, with no, or very little, admixture of superexchange.
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Affiliation(s)
- J T Kennis
- Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands
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