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Zazubovich V, Jankowiak R. High-Resolution Frequency-Domain Spectroscopic and Modeling Studies of Photosystem I (PSI), PSI Mutants and PSI Supercomplexes. Int J Mol Sci 2024; 25:3850. [PMID: 38612659 PMCID: PMC11011720 DOI: 10.3390/ijms25073850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/23/2024] [Accepted: 03/26/2024] [Indexed: 04/14/2024] Open
Abstract
Photosystem I (PSI) is one of the two main pigment-protein complexes where the primary steps of oxygenic photosynthesis take place. This review describes low-temperature frequency-domain experiments (absorption, emission, circular dichroism, resonant and non-resonant hole-burned spectra) and modeling efforts reported for PSI in recent years. In particular, we focus on the spectral hole-burning studies, which are not as common in photosynthesis research as the time-domain spectroscopies. Experimental and modeling data obtained for trimeric cyanobacterial Photosystem I (PSI3), PSI3 mutants, and PSI3-IsiA18 supercomplexes are analyzed to provide a more comprehensive understanding of their excitonic structure and excitation energy transfer (EET) processes. Detailed information on the excitonic structure of photosynthetic complexes is essential to determine the structure-function relationship. We will focus on the so-called "red antenna states" of cyanobacterial PSI, as these states play an important role in photochemical processes and EET pathways. The high-resolution data and modeling studies presented here provide additional information on the energetics of the lowest energy states and their chlorophyll (Chl) compositions, as well as the EET pathways and how they are altered by mutations. We present evidence that the low-energy traps observed in PSI are excitonically coupled states with significant charge-transfer (CT) character. The analysis presented for various optical spectra of PSI3 and PSI3-IsiA18 supercomplexes allowed us to make inferences about EET from the IsiA18 ring to the PSI3 core and demonstrate that the number of entry points varies between sample preparations studied by different groups. In our most recent samples, there most likely are three entry points for EET from the IsiA18 ring per the PSI core monomer, with two of these entry points likely being located next to each other. Therefore, there are nine entry points from the IsiA18 ring to the PSI3 trimer. We anticipate that the data discussed below will stimulate further research in this area, providing even more insight into the structure-based models of these important cyanobacterial photosystems.
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Affiliation(s)
- Valter Zazubovich
- Department of Physics, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Ryszard Jankowiak
- Department of Chemistry, Kansas State University, Manhattan, KS 66506, USA
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Zhang X, Taniguchi R, Nagao R, Tomo T, Noguchi T, Ye S, Shibata Y. Access to the Antenna System of Photosystem I via Single-Molecule Excitation-Emission Spectroscopy. J Phys Chem B 2024; 128:2664-2674. [PMID: 38456814 DOI: 10.1021/acs.jpcb.3c07789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
In the development of single-molecule spectroscopy, the simultaneous detection of the excitation and emission spectra has been limited. The fluorescence excitation spectrum based on background-free signals is compatible with the fluorescence-emission-based detection of single molecules and can provide insight into the variations in the input energy of the different terminal emitters. Here, we implement single-molecule excitation-emission spectroscopy (SMEES) for photosystem I (PSI) via a cryogenic optical microscope. To this end, we extended our line-focus-based excitation-spectral microscope system to the cryogenic temperature-compatible version. PSI is one of the two photosystems embedded in the thylakoid membrane in oxygen-free photosynthetic organisms. PSI plays an essential role in electron transfer in the photosynthesis reaction. PSIs of many organisms contain a few red-shifted chlorophylls (Chls) with much lower excitation energies than ordinary antenna Chls. The fluorescence emission spectrum originates primarily from the red-shifted Chls, whereas the excitation spectrum is sensitive to the antenna Chls that are upstream of red-shifted Chls. Using SMEES, we obtained the inclining two-dimensional excitation-emission matrix (2D-EEM) of PSI particles isolated from a cyanobacterium, Thermosynechococcus vestitus (equivalent to elongatus), at about 80 K. Interestingly, by decomposing the inclining 2D-EEMs within time course observation, we found prominent variations in the excitation spectra of the red-shifted Chl pools with different emission wavelengths, strongly indicating the variable excitation energy transfer (EET) pathway from the antenna to the terminal emitting pools. SMEES helps us to directly gain information about the antenna system, which is fundamental to depicting the EET within pigment-protein complexes.
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Affiliation(s)
- Xianjun Zhang
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai 980-8578, Japan
- Division for Interdisciplinary Advanced Research and Education, Tohoku University, Sendai 980-8578, Japan
| | - Rin Taniguchi
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Ryo Nagao
- Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan
| | - Tatsuya Tomo
- Department of Physics, Graduate School of Sciences, Tokyo University of Science, Tokyo 162-8601, Japan
| | - Takumi Noguchi
- Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Shen Ye
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Yutaka Shibata
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai 980-8578, Japan
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Hayase T, Shimada Y, Mitomi T, Nagao R, Noguchi T. Triplet Delocalization over the Reaction Center Chlorophylls in Photosystem II. J Phys Chem B 2023; 127:1758-1770. [PMID: 36809007 DOI: 10.1021/acs.jpcb.3c00139] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The triplet state of chlorophyll formed by charge recombination in photosystem II (PSII) is a precursor of harmful singlet oxygen. Although main localization of the triplet state on the monomeric chlorophyll, ChlD1, at cryogenic temperatures has been suggested, how the triplet state is delocalized on other chlorophylls remains unclear. Here, we investigated the distribution of the triplet state of chlorophyll in PSII using light-induced Fourier transform infrared (FTIR) difference spectroscopy. Measurements of triplet-minus-singlet FTIR difference spectra with PSII core complexes from cyanobacterial mutants, D1-V157H, D2-V156H, D2-H197A, and D1-H198A, in which the interactions of the 131-keto C═O groups of the reaction center chlorophylls, PD1, PD2, ChlD1, and ChlD2, respectively, were perturbed, identified the 131-keto C═O bands of the individual chlorophylls and showed that the triplet state is delocalized over all of these chlorophylls. It is suggested that the triplet delocalization plays important roles in the photoprotection and photodamage mechanisms in PSII.
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Affiliation(s)
- Taichi Hayase
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Yuichiro Shimada
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Tatsuya Mitomi
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Ryo Nagao
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.,Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan
| | - Takumi Noguchi
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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Kondo T, Shibata Y. Recent advances in single-molecule spectroscopy studies on light-harvesting processes in oxygenic photosynthesis. Biophys Physicobiol 2022. [PMCID: PMC9173860 DOI: 10.2142/biophysico.bppb-v19.0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Photosynthetic light-harvesting complexes (LHCs) play a crucial role in concentrating the photon energy from the sun that otherwise excites a typical pigment molecule, such as chlorophyll-a, only several times a second. Densely packed pigments in the complexes ensure efficient energy transfer to the reaction center. At the same time, LHCs have the ability to switch to an energy-quenching state and thus play a photoprotective role under excessive light conditions. Photoprotection is especially important for oxygenic photosynthetic organisms because toxic reactive oxygen species can be generated through photochemistry under aerobic conditions. Because of the extreme complexity of the systems in which various types of pigment molecules strongly interact with each other and with the surrounding protein matrixes, there has been long-standing difficulty in understanding the molecular mechanisms underlying the flexible switching between the light-harvesting and quenching states. Single-molecule spectroscopy studies are suitable to reveal the conformational dynamics of LHCs reflected in the fluorescence properties that are obscured in ordinary ensemble measurements. Recent advanced single-molecule spectroscopy studies have revealed the dynamical fluctuations of LHCs in their fluorescence peak position, intensity, and lifetime. The observed dynamics seem relevant to the conformational plasticity required for the flexible activations of photoprotective energy quenching. In this review, we survey recent advances in the single-molecule spectroscopy study of the light-harvesting systems of oxygenic photosynthesis.
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Affiliation(s)
- Toru Kondo
- School of Life Science and Technology, Tokyo Institute of Technology
| | - Yutaka Shibata
- Department of Chemistry, Graduate School of Science, Tohoku University
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Khmelnitskiy A, Toporik H, Mazor Y, Jankowiak R. On the Red Antenna States of Photosystem I Mutants from Cyanobacteria Synechocystis PCC 6803. J Phys Chem B 2020; 124:8504-8515. [DOI: 10.1021/acs.jpcb.0c05201] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anton Khmelnitskiy
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
| | - Hila Toporik
- School of Molecular Sciences and The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Yuval Mazor
- School of Molecular Sciences and The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Ryszard Jankowiak
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
- Department of Physics, Kansas State University, Manhattan, Kansas 66506, United States
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Jana D, Jana S. Donor-Pyrene-Acceptor Distance-Dependent Intramolecular Charge-Transfer Process: A State-Specific Solvation Preferred to the Linear-Response Approach. ACS OMEGA 2020; 5:9944-9956. [PMID: 32391482 PMCID: PMC7203991 DOI: 10.1021/acsomega.0c00265] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 04/07/2020] [Indexed: 05/15/2023]
Abstract
Photoinduced intramolecular charge-transfer (ICT) molecules are important in various applications such as a probe for single-molecule spectroscopy, cell imaging, laser dyes, biomarkers, solar cells, in photosynthesis, etc. Here, we report a new set of substituted pyrene dye molecules, N,N-dimethylamino nitrilo pyrene and its higher analogues, containing pull-push donor (D)-chromophore (π)-acceptor (A) functional groups with enhanced photophysical characteristics like oscillator strength, light-harvesting, and ICT properties. The excited-state ICT process has been established by quantum chemical calculations using the density functional theory method in vacuo and in solvents of different polarity and hydrogen-bonding ability using linear-response (LR) and state-specific (SS) solvation approaches with gradually increasing the D-A distance. The studied molecules show solvent polarity-dependent larger Stokes' shifts (3609-9016 cm-1, in acetonitrile), higher excited-state dipole moments (11.7-16.8 Debye, in acetonitrile), higher possibilities of highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) electronic transitions, etc., which support the occurrence of the excited-state ICT process. Here, we demonstrate how to increase the efficiency of the ICT process and also tune the ICT fluorescence maximum. We find that with a variation of the D-A distance, studied molecules show a noticeable effect on the spectroscopic and molecular properties such as the position of absorption and fluorescence band maxima, Stokes' shift, dipole moment, light-harvesting, and ICT properties. We also show that the SS solvation approach is more supportive than the LR method to the ICT process.
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Affiliation(s)
- Dipanwita Jana
- Bishnupada
Sarkar College of Education, Gourhati,
Arambagh, Hooghly, West Bengal 712613, India
| | - Sankar Jana
- School
of Biology, Biomedical Science Research Complex, University of St Andrews, North
Haugh, St Andrews, Fife KY16 9ST, United Kingdom
- . Tel: +44 (0)1334 463401. Fax: +44 (0)1334 462595
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