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Reinot T, Khmelnitskiy A, Zazubovich V, Toporik H, Mazor Y, Jankowiak R. Frequency-Domain Spectroscopic Study of the Photosystem I Supercomplexes, Isolated IsiA Monomers, and the Intact IsiA Ring. J Phys Chem B 2022; 126:6891-6910. [PMID: 36065077 DOI: 10.1021/acs.jpcb.2c04829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The PSI3-IsiA18 supercomplex is one of the largest and most complicated assemblies in photosynthesis. The IsiA ring, composed of 18 IsiA monomers (IsiA18) surrounding the PSI trimer (PSI3), forms under iron-deficient conditions in cyanobacteria and acts as a peripheral antenna. Based on the supercomplex structure recently determined via cryo-EM imaging, we model various optical spectra of the IsiA monomers and IsiA18 ring. Comparison of the absorption and emission spectra of the isolated IsiA monomers and the full ring reveals that about 2.7 chlorophylls (Chls) are lost in the isolated IsiA monomers. The best fits for isolated monomers spectra are obtained assuming the absence of Chl 508 and Chl 517 and 70% loss of Chl 511. The best model describing all three hexamers and the entire ring suggests that the lowest energy pigments are Chls 511, 514, and 517. Based on the modeling results presented in this work, we conclude that there are most likely three entry points for EET from the IsiA6 hexamer to the PSI core monomer, with two of these entry points likely being located next to each other (i.e., nine entry points from IsiA18 to the PSI3 trimer). Finally, we show that excitation energy transfer inside individual monomers is fast (<2 ps at T = 5 K) and at least 20 times faster than intermonomer energy transfer.
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Affiliation(s)
| | | | - Valter Zazubovich
- Department of Physics, Concordia University, Montreal, H4B 1R6, Canada
| | - Hila Toporik
- School of Molecular Sciences and Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, Arizona 85287, United States
| | - Yuval Mazor
- School of Molecular Sciences and Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, Arizona 85287, United States
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Kell A, Khmelnitskiy AY, Reinot T, Jankowiak R. On uncorrelated inter-monomer Förster energy transfer in Fenna-Matthews-Olson complexes. J R Soc Interface 2020; 16:20180882. [PMID: 30958204 DOI: 10.1098/rsif.2018.0882] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The Fenna-Matthews-Olson (FMO) light-harvesting antenna protein of green sulfur bacteria is a long-studied pigment-protein complex which funnels energy from the chlorosome to the reaction centre where photochemistry takes place. The structure of the FMO protein from Chlorobaculum tepidum is known as a homotrimeric complex containing eight bacteriochlorophyll a per monomer. Owing to this structure FMO has strong intra-monomer and weak inter-monomer electronic coupling constants. While long-lived (sub-picosecond) coherences within a monomer have been a prevalent topic of study over the past decade, various experimental evidence supports the presence of subsequent inter-monomer energy transfer on a picosecond time scale. The latter has been neglected by most authors in recent years by considering only sub-picosecond time scales or assuming that the inter-monomer coupling between low-energy states is too weak to warrant consideration of the entire trimer. However, Förster theory predicts that energy transfer of the order of picoseconds is possible even for very weak (less than 5 cm-1) electronic coupling between chromophores. This work reviews experimental data (with a focus on emission and hole-burned spectra) and simulations of exciton dynamics which demonstrate inter-monomer energy transfer. It is shown that the lowest energy 825 nm absorbance band cannot be properly described by a single excitonic state. The energy transfer through FMO is modelled by generalized Förster theory using a non-Markovian, reduced density matrix approach to describe the electronic structure. The disorder-averaged inter-monomer transfer time across the 825 nm band is about 27 ps. While only isolated FMO proteins are presented, the presence of inter-monomer energy transfer in the context of the overall photosystem is also briefly discussed.
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Affiliation(s)
- Adam Kell
- 1 Department of Chemistry, Kansas State University , Manhattan, KS , USA
| | | | - Tonu Reinot
- 1 Department of Chemistry, Kansas State University , Manhattan, KS , USA
| | - Ryszard Jankowiak
- 1 Department of Chemistry, Kansas State University , Manhattan, KS , USA.,2 Department of Physics, Kansas State University , Manhattan, KS , USA
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Zazubovich V, Jankowiak R. How Well Does the Hole-Burning Action Spectrum Represent the Site-Distribution Function of the Lowest-Energy State in Photosynthetic Pigment-Protein Complexes? J Phys Chem B 2019; 123:6007-6013. [PMID: 31265294 DOI: 10.1021/acs.jpcb.9b03806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For the first time, we combined Monte Carlo and nonphotochemical hole burning (NPHB) master equation approaches to allow for ultrahigh-resolution (<0.005 cm-1, smaller than the typical homogeneous line widths at 5 K) simulations of the NPHB spectra of dimers and trimers of interacting pigments. These simulations reveal significant differences between the zero-phonon hole (ZPH) action spectrum and the site-distribution function (SDF) of the lowest-energy state. The NPHB of the lowest-energy pigment, following the excitation energy transfer (EET) from the higher-energy pigments which are excited directly, results in the shifts of all excited states. These shifts affect the ZPH action spectra and EET times derived from the widths of the spectral holes burned in the donor-dominated regions. The effect is present for a broad variety of realistic antihole functions, and it is maximal at relatively low values of interpigment coupling (V ≤ 5 cm-1) where the use of the Förster approximation is justified. These findings need to be considered in interpreting various optical spectra of photosynthetic pigment-protein complexes for which SDFs (describing the inhomogeneous broadening) are often obtained directly from the ZPH action spectra. Water-soluble chlorophyll-binding protein (WSCP) was considered as an example.
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Affiliation(s)
- Valter Zazubovich
- Department of Physics , Concordia University , 7141 Sherbrooke Street West , Montreal H4B 1R6 , Quebec , Canada
| | - Ryszard Jankowiak
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506 , United States
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Saer RG, Schultz RL, Blankenship RE. The influence of quaternary structure on the stability of Fenna-Matthews-Olson (FMO) antenna complexes. PHOTOSYNTHESIS RESEARCH 2019; 140:39-49. [PMID: 30315435 DOI: 10.1007/s11120-018-0591-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/03/2018] [Indexed: 06/08/2023]
Abstract
The trimeric nature of the Fenna-Matthews-Olson (FMO) protein antenna complex from green sulfur phototrophic bacteria was investigated. Mutations were introduced into the protein at positions 142 and 198, which were chosen to destabilize the intra-trimer salt bridges between adjacent monomers. Strains bearing the mutations R142L, R198L, or their combination, exhibited altered optical absorption spectra of purified membranes and fluoresced more intensely than the wild type. In particular, the introduction of the R142L mutation resulted in slower culture growth rates, as well as an FMO complex that was not able to be isolated in appreciable quantities, while the R198L mutation yielded an FMO complex with increased sensitivity to sodium thiocyanate and Triton X-100 treatments. Native and denaturing PAGE experiments suggest that much of the FMO complexes in the mutant strains pool with the insoluble material upon membrane solubilization with n-dodecyl β-D-maltoside, a mild nonionic detergent. Taken together, our results suggest that the quaternary structure of the FMO complex, the homotrimer, is an important factor in the maintenance of the complex's tertiary structure.
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Affiliation(s)
- Rafael G Saer
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA
| | - Rebecca L Schultz
- Department of Chemistry, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA
- Department of Chemistry, University of Wisconsin Madison, Madison, WI, 53706, USA
| | - Robert E Blankenship
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA.
- Department of Chemistry, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO, 63130, USA.
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Khmelnitskiy A, Saer RG, Blankenship RE, Jankowiak R. Excitonic Energy Landscape of the Y16F Mutant of the Chlorobium tepidum Fenna-Matthews-Olson (FMO) Complex: High Resolution Spectroscopic and Modeling Studies. J Phys Chem B 2018; 122:3734-3743. [PMID: 29554425 DOI: 10.1021/acs.jpcb.7b11763] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We report high-resolution (low-temperature) absorption, emission, and nonresonant/resonant hole-burned (HB) spectra and results of excitonic calculations using a non-Markovian reduced density matrix theory (with an improved algorithm for parameter optimization in heterogeneous samples) obtained for the Y16F mutant of the Fenna-Matthews-Olson (FMO) trimer from the green sulfur bacterium Chlorobium tepidum. We show that the Y16F mutant is a mixture of FMO complexes with three independent low-energy traps (located near 817, 821, and 826 nm), in agreement with measured composite emission and HB spectra. Two of these traps belong to mutated FMO subpopulations characterized by significantly modified low-energy excitonic states. Hamiltonians for the two major subpopulations (Sub821 and Sub817) provide new insight into extensive changes induced by the single-point mutation in the vicinity of BChl 3 (where tyrosine Y16 was replaced with phenylalanine F16). The average decay time(s) from the higher exciton state(s) in the Y16F mutant depends on frequency and occurs on a picosecond time scale.
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Affiliation(s)
| | - Rafael G Saer
- Departments of Biology and Chemistry , Washington University in St. Louis , Saint Louis , Missouri 63130 , United States
| | - Robert E Blankenship
- Departments of Biology and Chemistry , Washington University in St. Louis , Saint Louis , Missouri 63130 , United States
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Khmelnitskiy A, Kell A, Reinot T, Saer RG, Blankenship RE, Jankowiak R. Energy landscape of the intact and destabilized FMO antennas from C. tepidum and the L122Q mutant: Low temperature spectroscopy and modeling study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:165-173. [DOI: 10.1016/j.bbabio.2017.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 11/23/2017] [Accepted: 11/27/2017] [Indexed: 12/21/2022]
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Tiwari V, Jonas DM. Electronic energy transfer through non-adiabatic vibrational-electronic resonance. II. 1D spectra for a dimer. J Chem Phys 2018; 148:084308. [DOI: 10.1063/1.5003193] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Vivek Tiwari
- Department of Chemistry and Biochemistry, University of Colorado, 215 UCB, Boulder, Colorado 80309, USA
| | - David M. Jonas
- Department of Chemistry and Biochemistry, University of Colorado, 215 UCB, Boulder, Colorado 80309, USA
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Kell A, Blankenship RE, Jankowiak R. Effect of Spectral Density Shapes on the Excitonic Structure and Dynamics of the Fenna–Matthews–Olson Trimer from Chlorobaculum tepidum. J Phys Chem A 2016; 120:6146-54. [DOI: 10.1021/acs.jpca.6b03107] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | - Robert E. Blankenship
- Departments
of Chemistry and Biology, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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Challenges facing an understanding of the nature of low-energy excited states in photosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1627-1640. [PMID: 27372198 DOI: 10.1016/j.bbabio.2016.06.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/27/2016] [Accepted: 06/28/2016] [Indexed: 01/09/2023]
Abstract
While the majority of the photochemical states and pathways related to the biological capture of solar energy are now well understood and provide paradigms for artificial device design, additional low-energy states have been discovered in many systems with obscure origins and significance. However, as low-energy states are naively expected to be critical to function, these observations pose important challenges. A review of known properties of low energy states covering eight photochemical systems, and options for their interpretation, are presented. A concerted experimental and theoretical research strategy is suggested and outlined, this being aimed at providing a fully comprehensive understanding.
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Kell A, Bednarczyk D, Acharya K, Chen J, Noy D, Jankowiak R. New Insight into the Water-Soluble Chlorophyll-Binding Protein fromLepidium virginicum. Photochem Photobiol 2016; 92:428-35. [DOI: 10.1111/php.12581] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/18/2016] [Indexed: 01/20/2023]
Affiliation(s)
- Adam Kell
- Department of Chemistry; Kansas State University; Manhattan Kansas 66506
| | - Dominika Bednarczyk
- Department of Biological Chemistry; Weizmann Institute of Sciences; Rehovot 76100 Israel
| | - Khem Acharya
- Department of Chemistry; Kansas State University; Manhattan Kansas 66506
| | - Jinhai Chen
- Department of Chemistry; Kansas State University; Manhattan Kansas 66506
| | - Dror Noy
- Migal-Galilee Research Institute; Kiryat Shmona 11016 Israel
| | - Ryszard Jankowiak
- Department of Chemistry; Kansas State University; Manhattan Kansas 66506
- Department of Physics; Kansas State University; Manhattan Kansas 66506
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Najafi M, Herascu N, Shafiei G, Picorel R, Zazubovich V. Conformational Changes in Pigment–Protein Complexes at Low Temperatures—Spectral Memory and a Possibility of Cooperative Effects. J Phys Chem B 2015; 119:6930-40. [PMID: 25985255 DOI: 10.1021/acs.jpcb.5b02845] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mehdi Najafi
- Department
of Physics, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
| | - Nicoleta Herascu
- Department
of Physics, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
| | - Golia Shafiei
- Department
of Physics, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
| | - Rafael Picorel
- Estacion Experimental de Aula Dei (CSIC), Avda. Montañana 1005, 50059 Zaragoza, Spain
| | - Valter Zazubovich
- Department
of Physics, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
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Zazubovich V. Fluorescence Line Narrowing and Δ-FLN Spectra in the Presence of Excitation Energy Transfer between Weakly Coupled Chromophores. J Phys Chem B 2014; 118:13535-43. [DOI: 10.1021/jp509056z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Valter Zazubovich
- Department of Physics, Concordia University, 7141 Sherbrooke Street West, Montreal H4B 1R6, Quebec, Canada
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Kell A, Acharya K, Zazubovich V, Jankowiak R. On the Controversial Nature of the 825 nm Exciton Band in the FMO Protein Complex. J Phys Chem Lett 2014; 5:1450-1456. [PMID: 26269993 DOI: 10.1021/jz5001165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The nature of the low-energy 825 nm band of the Fenna-Matthews-Olson (FMO) protein complex from Chlorobaculum tepidum at 5 K is discussed. It is shown, using hole-burning (HB) spectroscopy and excitonic calculations, that the 825 nm absorption band of the FMO trimer cannot be explained by a single electronic transition or overlap of electronic transitions of noninteracting pigments. To explain the shape of emission and nonresonant HB spectra, downward uncorrelated excitation energy transfer (EET) between trimer subunits should be taken into account. Modeling studies reveal the presence of three sub-bands within the 825 nm band, in agreement with nonresonant HB and emission spectra. We argue that after light induced coherences vanish, uncorrelated EET between the lowest exciton levels of each monomer takes place. HB induced spectral shifts provide a new insight on the energy landscape of the FMO protein.
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Affiliation(s)
| | | | - Valter Zazubovich
- §Department of Physics, Concordia University, Montreal H4B 1R6, Quebec, Canada
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