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Switching sides-Reengineered primary charge separation in the bacterial photosynthetic reaction center. Proc Natl Acad Sci U S A 2019; 117:865-871. [PMID: 31892543 DOI: 10.1073/pnas.1916119117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report 90% yield of electron transfer (ET) from the singlet excited state P* of the primary electron-donor P (a bacteriochlorophyll dimer) to the B-side bacteriopheophytin (HB) in the bacterial photosynthetic reaction center (RC). Starting from a platform Rhodobacter sphaeroides RC bearing several amino acid changes, an Arg in place of the native Leu at L185-positioned over one face of HB and only ∼4 Å from the 4 central nitrogens of the HB macrocycle-is the key additional mutation providing 90% yield of P+HB - This all but matches the near-unity yield of A-side P+HA - charge separation in the native RC. The 90% yield of ET to HB derives from (minimally) 3 P* populations with distinct means of P* decay. In an ∼40% population, P* decays in ∼4 ps via a 2-step process involving a short-lived P+BB - intermediate, analogous to initial charge separation on the A side of wild-type RCs. In an ∼50% population, P* → P+HB - conversion takes place in ∼20 ps by a superexchange mechanism mediated by BB An ∼10% population of P* decays in ∼150 ps largely by internal conversion. These results address the long-standing dichotomy of A- versus B-side initial charge separation in native RCs and have implications for the mechanism(s) and timescale of initial ET that are required to achieve a near-quantitative yield of unidirectional charge separation.
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Faries KM, Dylla NP, Hanson DK, Holten D, Laible PD, Kirmaier C. Manipulating the Energetics and Rates of Electron Transfer in Rhodobacter capsulatus Reaction Centers with Asymmetric Pigment Content. J Phys Chem B 2017; 121:6989-7004. [DOI: 10.1021/acs.jpcb.7b01389] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kaitlyn M. Faries
- Department
of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Nicholas P. Dylla
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Deborah K. Hanson
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Dewey Holten
- Department
of Chemistry, Washington University, 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, St. Louis, Missouri 63130, United States
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Faries KM, Kressel LL, Dylla NP, Wander MJ, Hanson DK, Holten D, Laible PD, Kirmaier C. Optimizing multi-step B-side charge separation in photosynthetic reaction centers from Rhodobacter capsulatus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:150-159. [DOI: 10.1016/j.bbabio.2015.11.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 11/20/2015] [Accepted: 11/30/2015] [Indexed: 11/16/2022]
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Kressel L, Faries KM, Wander MJ, Zogzas CE, Mejdrich RJ, Hanson DK, Holten D, Laible PD, Kirmaier C. High yield of secondary B-side electron transfer in mutant Rhodobacter capsulatus reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1892-1903. [DOI: 10.1016/j.bbabio.2014.07.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/22/2014] [Accepted: 07/26/2014] [Indexed: 10/25/2022]
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Takahashi R, Hasegawa K, Noguchi T. Effect of charge distribution over a chlorophyll dimer on the redox potential of P680 in photosystem II as studied by density functional theory calculations. Biochemistry 2008; 47:6289-91. [PMID: 18500822 DOI: 10.1021/bi8007998] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of charge distribution over a chlorophyll dimer on the redox potential of P680 in photosystem II was studied by density functional theory calculations using the P680 coordinates in the X-ray structure. From the calculated ionization potentials of the dimer and the monomeric constituents, the decrease in the redox potential by charge delocalization over the dimer was estimated to be approximately 140 mV. Such charge delocalization was previously observed in the isolated D1-D2-Cyt b 559 complexes, whereas the charge was primarily localized on P D1 in the core complexes. The calculated potential decrease of approximately 140 mV can explain the inhibition of Y Z oxidation in the former complexes and in turn implies that the charge localization on P D1 upon formation of the core complex increases the P680 potential to the level necessary for water oxidation.
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Affiliation(s)
- Ryouta Takahashi
- Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
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Kirmaier C, Bautista JA, Laible PD, Hanson DK, Holten D. Probing the Contribution of Electronic Coupling to the Directionality of Electron Transfer in Photosynthetic Reaction Centers. J Phys Chem B 2005; 109:24160-72. [PMID: 16375408 DOI: 10.1021/jp054726z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Subpicosecond transient absorption studies are reported for a set of Rhodobacter (R.) capsulatus bacterial photosynthetic reaction centers (RCs) designed to probe the origins of the unidirectionality of charge separation via one of two electron transport chains in the native pigment-protein complex. All of the RCs have been engineered to contain a heterodimeric primary electron donor (D) consisting of a bacteriochlorophyll (BChl) and a bacteriopheophytin (BPh). The BPh component of the M heterodimer (Mhd) or L heterodimer (Lhd) is introduced by substituting a Leu for His M200 or His L173, respectively. Previous work on primary charge separation in heterodimer mutants has not included the Lhd RC from R. capsulatus, which we report for the first time. The Lhd and Mhd RCs are used as controls against which we assess RCs that combine the heterodimer mutations with a second mutation (His substituted for Leu at M212) that results in replacement of the native L-side BPh acceptor with a BChl (beta). The transient absorption spectra reveal clear evidence for charge separation to the normally inactive M-side BPh acceptor (H(M)) in Lhd-beta RCs to form D+H(M)- with a yield of approximately 6%. This state also forms in Mhd-beta RCs but with about one-quarter the yield. In both RCs, deactivation to the ground state is the predominant pathway of D decay, as it is in the Mhd and Lhd single mutants. Analysis of the results indicates an upper limit ofV2L/V2m < or = 4 for the contribution of the electronic coupling elements to the relative rates of electron transfer to the L versus M sides of the wild-type RC. In comparison to the L/M rate ratio (kL/kM) approximately 30 for wild-type RCs, our findings indicate that electronic factors contribute approximately 35% at most to directionality with the other 65% deriving from energetic considerations, which includes differences in free energies, reorganization energies, and contributions of one- and two-step mechanisms on the two sides of the RC.
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Affiliation(s)
- Christine Kirmaier
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA
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7
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King BA, McAnaney TB, de Winter A, Boxer SG. Excited-state energy transfer pathways in photosynthetic reaction centers: 5. Oxidized and triplet excited special pairs as energy acceptors. Chem Phys 2003. [DOI: 10.1016/s0301-0104(03)00318-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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8
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King BA, de Winter A, McAnaney TB, Boxer SG. Excited State Energy Transfer Pathways in Photosynthetic Reaction Centers. 4. Asymmetric Energy Transfer in the Heterodimer Mutant. J Phys Chem B 2001. [DOI: 10.1021/jp002318j] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Brett A. King
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Alex de Winter
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Tim B. McAnaney
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
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van Brederode ME, van Grondelle R. New and unexpected routes for ultrafast electron transfer in photosynthetic reaction centers. FEBS Lett 1999; 455:1-7. [PMID: 10428460 DOI: 10.1016/s0014-5793(99)00810-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In photosynthetic reaction centers, the excitation with light leads to the formation of a charge separated state across the photosynthetic membrane. For the reaction center of purple non-sulphur bacteria, it was previously generally assumed that this primary charge separation could only start with the excitation of the so-called special pair of bacteriochlorophyll molecules located in the heart of the RC. However, recently new and ultrafast pathways of charge separation have been discovered in the bacterial RC that are driven directly by the excited state of the accessory monomeric bacteriochlorophyll present in the active branch of cofactors. These results demonstrate that the route for energy conversion in photosynthesis can be much more flexible than previously thought. We suggest that the existence of multiple charge separation routes is particularly relevant for the mechanism of charge separation in the photosystem II reaction center of higher plants.
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Affiliation(s)
- M E van Brederode
- Department of Biophysics and Physics of Complex Systems, Vrije Universiteit and Institute of Molecular Biological Sciences (IMBW), Vrije Universiteit, Amsterdam, The Netherlands
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Buranda T, Enlow M, Griener J, Soice N, Ondrias M. Singlet-State Electron Transfer between a Porphyrin and Ubiquinone: A Transient Resonance Raman and Quantum Chemical Study. J Phys Chem B 1998. [DOI: 10.1021/jp980168v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tione Buranda
- The Department of Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131
| | - Mark Enlow
- The Department of Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131
| | - Jack Griener
- The Department of Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131
| | - Neal Soice
- The Department of Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131
| | - Mark Ondrias
- The Department of Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131
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Haselbach E, Pilloud D, Suppan P. Orbital-Symmetry Effects in Bimolecular Electron-Transfer Reactions: Back Electron Transfer. Helv Chim Acta 1998. [DOI: 10.1002/hlca.19980810317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Arnaut LG, Formosinho SJ. Theory of electron transfer reactions in photosynthetic bacteria reaction centers. J Photochem Photobiol A Chem 1997. [DOI: 10.1016/s1010-6030(97)00225-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Albouy D, Kuhn M, Williams J, Allen J, Lubitz W, Mattioli T. Fourier transform Raman investigation of the electronic structure and charge localization in a bacteriochlorophyll-bacteriopheophytin dimer of reaction centers from Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1997. [DOI: 10.1016/s0005-2728(97)00044-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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King BA, Stanley RJ, Boxer SG. Excited State Energy Transfer Pathways in Photosynthetic Reaction Centers. 2. Heterodimer Special Pair. J Phys Chem B 1997. [DOI: 10.1021/jp964025p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brett A. King
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Robert J. Stanley
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
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15
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Laporte LL, Palaniappan V, Davis DG, Kirmaier C, Schenck CC, Holten D, Bocian DF. Influence of Electronic Asymmetry on the Spectroscopic and Photodynamic Properties of the Primary Electron Donor in the Photosynthetic Reaction Center. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp961658v] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Laurent L. Laporte
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
| | - Vaithianathan Palaniappan
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
| | - Dianna G. Davis
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
| | - Christine Kirmaier
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
| | - Craig C. Schenck
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
| | - Dewey Holten
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
| | - David F. Bocian
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, Department of Chemistry, University of California at Riverside, Riverside, California 92521, and Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523
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Electronic structure of the oxidized primary electron donor of the HL (M202) and HL (L173) heterodimer mutants of the photosynthetic bacterium Rhodobacter sphaeroides: ENDOR on single crystals of reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1996. [DOI: 10.1016/0005-2728(95)00134-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Palaniappan V, Bocian DF. Resonance Raman characterization of H(M200)L mutant reaction centers from Rhodobacter capsulatus. Effects of heterodimer formation on the structural and electronic properties of the cofactors. Biochemistry 1995; 34:11106-16. [PMID: 7669768 DOI: 10.1021/bi00035a016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Resonance Raman (RR) spectra are reported for photosynthetic reactions centers (RCs) from the H(M200)L mutant of Rhodobacter capsulatus. In this mutant, the histidine residue which ligates the M-side bacteriochlorophyll (BCh) of the special pair primary donor (P) of wild-type RCs is replaced by a noncoordinating leucine. This results in the formation of a heterodimer primary donor (D) in which a bacteriopheophytin (BPh) replaces the M-side BCh. The RR data for the H(M200)L mutant were acquired at a large number of excitation wavelengths which span the B, Qx, and Qy absorption bands of the various bacteriochlorin cofactors in the RC. For comparison, spectra were also acquired for wild-type RCs at the same excitation wavelengths. The RR data obtained for the mutant indicate that heterodimer formation induces a variety of changes in the structural and electronic properties of the cofactors in the RC. These perturbations extend beyond the primary donor and include one of the two accessory BChs. Collectively, the RR studies indicate the following: (1) The structure of the single BCh cofactor in D [DL(BCh)] is different from that of either of the two BChs in P. However, DL(BCh) is more similar to PL than to PM. The PM cofactor is conformationally more distorted than either PL or DL(BCh). (2) The structure of the BPh cofactor in D [DM(BPh)] is similar to that of the other two BPhs in the RC. However, the frequency of the C9-keto carbonyl mode of DM(BPh) is anomalously low (1678 cm-1), as is also the case for PM. The vibrational characteristics of the C9-keto carbonyl vibrations of DM(BPh)/PM versus DL(BCh)/PL are consistent the notion that dielectric effects govern the frequency of the mode and that the effective dielectric constant is different on the L- versus M-sides of the primary donor. (3) Heterodimer formation perturbs the structural and electronic properties of one of the two accessory BChs (most likely BChL) in the RC. These perturbations are manifested as upshifts in the ring skeletal-mode frequencies and a blue-shift in the Qx absorption band (from 600 to 580 nm). The fact that heterodimer formation perturbs one of the accessory BChs suggests that global structural rearrangements occur in the protein matrix when the ligand to a cofactor in the primary donor is removed. (4) For both the H(M200)L mutant and wild-type RCs, oxidation of the primary donor significantly affects the RR cross section of the carotenoid.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- V Palaniappan
- Department of Chemistry, University of California, Riverside 92521-0403, USA
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Heller BA, Holten D, Kirmaier C. Control of electron transfer between the L- and M-sides of photosynthetic reaction centers. Science 1995; 269:940-5. [PMID: 7638616 DOI: 10.1126/science.7638616] [Citation(s) in RCA: 170] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An aspartic acid residue has been introduced near ring V of the L-side accessory bacteriochlorophyll (BCHlL) or the photosynthetic reaction center in a rhodobacter capsulatus mutant in which a His also replaces Leu 212 on the M-polypeptide. The initial stage of charge separation in the G(M201)D/L(M212)H double mutant yields approximately 70 percent electron transfer to the L-side cofactors, approximately 15 percent rapid deactivation to the ground state, and approximately 15 percent electron transfer to the so-called inactive M-side bacteriopheophytin (BPhM). It is suggested here that the Asp introduced at M201 modulates the reduction potential of BCHlL, thereby changing the energetics of charge separation. The results demonstrate that an individual amino acid residue can, through its influence on the free energies of the charge-separated states, effectively dictate the balance between the forward electron transfer reactions on the L-side of the RC, the charge-recombination processes, and electron transfer to the M-side chromophores.
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Affiliation(s)
- B A Heller
- Department of Chemistry, Washington University, St Louis, MO 63130, USA
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Laporte L, Kirmaier C, Schenck CC, Holten D. Free-energy dependence of the rate of electron transfer to the primary quinone in beta-type reaction centers. Chem Phys 1995. [DOI: 10.1016/0301-0104(95)00036-n] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Frank HA, Innes J, Aldema M, Neumann R, Schenck CC. Triplet state EPR of reaction centers from the His(L173)→Leu (L173) mutant of Rhodobacter sphaeroides which contains a heterodimer primary donor. PHOTOSYNTHESIS RESEARCH 1993; 38:99-109. [PMID: 24317835 DOI: 10.1007/bf00015066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/1993] [Accepted: 08/11/1993] [Indexed: 06/02/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy has been used to examine the triplet states in reaction centers of Rhodobacter sphaeroides which have undergone a genetic modification affecting the primary donor. Reaction centers containing the His(L173)→Leu(L173) substitution in the amino acid sequence have a primary donor which consists of a BChl-BPh heterodimer. The triplets formed in this heterodimer reaction center were compared with those formed in the wild-type reaction center which contains the BChl-BChl homodimer. Both reaction centers transfer triplet energy to the carotenoid under illumination at liquid nitrogen temperatures (∼90 K). However, the intensity of the carotenoid triplet signal is significantly decreased in the Leu(L173) mutant compared with the wild-type reaction center. At 12 K, in wild-type reaction centers only the primary donor triplet is observed. The Leu(L173) mutant exhibits a signal similar to that observed by Bylina et al. (1990) in His(M200)→Leu(M200) mutant reaction centers from Rb. capsulatus. The values of the zero-field splitting parameters of this triplet are discussed within the context of various models for the primary donor triplet state. No alteration in the ability of the carotenoid to quench the primary donor triplet state results from mutations at these sites.
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Affiliation(s)
- H A Frank
- Department of Chemistry, University of Connecticut, 06269-3060, Storrs, CT, USA
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