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Cherepanov DA, Milanovsky GE, Neverov KV, Obukhov YN, Maleeva YV, Aybush AV, Kritsky MS, Nadtochenko VA. Exciton interactions of chlorophyll tetramer in water-soluble chlorophyll-binding protein BoWSCP. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 309:123847. [PMID: 38217986 DOI: 10.1016/j.saa.2024.123847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 01/02/2024] [Accepted: 01/03/2024] [Indexed: 01/15/2024]
Abstract
The exciton interaction of four chlorophyll a (Chl a) molecules in a symmetrical tetrameric complex of the water-soluble chlorophyll-binding protein BoWSCP was analyzed in the pH range of 3-11. Exciton splitting ΔE = 232 ± 2 cm-1 of the Qy band of Chl a into two subcomponents with relative intensities of 78.1 ± 0.7 % and 21.9 ± 0.7 % was determined by a joint decomposition of the absorption and circular dichroism spectra into Gaussian functions. The exciton coupling parameters were calculated based on the BoWSCP atomic structure in three approximations: the point dipole model, the distributed atomic monopoles, and direct ab initio calculations in the TDDFT/PCM approximation. The Coulomb interactions of monomers were calculated within the continuum model using three values of optical permittivity. The models based on the properties of free Chl a in solution suffer from significant errors both in estimating the absolute value of the exciton interaction and in the relative intensity of exciton transitions. Calculations within the TDDFT/PCM approximation reproduce the experimentally determined parameters of the exciton splitting and the relative intensities of the exciton bands. The following factors of pigment-protein and pigment-pigment interactions were examined: deviation of the macrocycle geometry from the planar conformation of free Chl; the formation of hydrogen bonds between the macrocycle and water molecules; the overlap of wave functions of monomers at close distances. The most significant factor is the geometrical deformation of the porphyrin macrocycle, which leads to an increase in the dipole moment of Chl monomer from 5.5 to 6.9 D and to a rotation of the dipole moment by 15° towards the cyclopentane ring. The contributions of resonant charge-transfer states to the wave functions of the Chl dimer were determined and the transition dipole moments of the symmetric and antisymmetric charge-transfer states were estimated.
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Affiliation(s)
- D A Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Kosygina str., 4, Russian Federation; A.N. Belozersky Institute Of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Leninskye gory, 1b.40, Russian Federation.
| | - G E Milanovsky
- A.N. Belozersky Institute Of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Leninskye gory, 1b.40, Russian Federation
| | - K V Neverov
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology", Russian Academy of Sciences", 119071 Moscow, Leninsky prospect, 33b.2, Russian Federation; Faculty of Biology, Moscow State University, 119234 Moscow, Leninskye gory, 1b.12, Russian Federation
| | - Yu N Obukhov
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology", Russian Academy of Sciences", 119071 Moscow, Leninsky prospect, 33b.2, Russian Federation
| | - Yu V Maleeva
- Faculty of Biology, Moscow State University, 119234 Moscow, Leninskye gory, 1b.12, Russian Federation
| | - A V Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Kosygina str., 4, Russian Federation
| | - M S Kritsky
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology", Russian Academy of Sciences", 119071 Moscow, Leninsky prospect, 33b.2, Russian Federation
| | - V A Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Kosygina str., 4, Russian Federation; Department of Chemistry, Moscow State University, 119991 Moscow, Leninskye gory, 1b.3, Russian Federation
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2
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Ranepura GA, Mao J, Vermaas JV, Wang J, Gisriel CJ, Wei RJ, Ortiz-Soto J, Uddin MR, Amin M, Brudvig GW, Gunner MR. Computing the Relative Affinity of Chlorophylls a and b to Light-Harvesting Complex II. J Phys Chem B 2023; 127:10974-10986. [PMID: 38097367 DOI: 10.1021/acs.jpcb.3c06273] [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: 12/29/2023]
Abstract
In plants and algae, the primary antenna protein bound to photosystem II is light-harvesting complex II (LHCII), a pigment-protein complex that binds eight chlorophyll (Chl) a molecules and six Chl b molecules. Chl a and Chl b differ only in that Chl a has a methyl group (-CH3) on one of its pyrrole rings, while Chl b has a formyl group (-CHO) at that position. This blue-shifts the Chl b absorbance relative to Chl a. It is not known how the protein selectively binds the right Chl type at each site. Knowing the selection criteria would allow the design of light-harvesting complexes that bind different Chl types, modifying an organism to utilize the light of different wavelengths. The difference in the binding affinity of Chl a and Chl b in pea and spinach LHCII was calculated using multiconformation continuum electrostatics and free energy perturbation. Both methods have identified some Chl sites where the bound Chl type (a or b) has a significantly higher affinity, especially when the protein provides a hydrogen bond for the Chl b formyl group. However, the Chl a sites often have little calculated preference for one Chl type, so they are predicted to bind a mixture of Chl a and b. The electron density of the spinach LHCII was reanalyzed, which, however, confirmed that there is negligible Chl b in the Chl a-binding sites. It is suggested that the protein chooses the correct Chl type during folding, segregating the preferred Chl to the correct binding site.
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Affiliation(s)
- Gehan A Ranepura
- Ph.D. Program in Physics, The Graduate Center, City University of New York, New York, New York 10016, United States
- Department of Physics, City College of New York, New York, New York 10031, United States
| | - Junjun Mao
- Benjamin Levich Institute for Physico-Chemical Hydrodynamics, City College of New York, New York, New York 10031, United States
| | - Josh V Vermaas
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, 612 Wilson Road, East Lansing, Michigan 48824, United States
| | - Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Christopher J Gisriel
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Rongmei Judy Wei
- Department of Physics, City College of New York, New York, New York 10031, United States
- Ph.D. Program in Chemistry, The Graduate Center, City University of New York, New York, New York 10016, United States
| | - Jose Ortiz-Soto
- Department of Physics, City College of New York, New York, New York 10031, United States
- Ph.D. Program in Chemistry, The Graduate Center, City University of New York, New York, New York 10016, United States
| | - Md Raihan Uddin
- Department of Physics, City College of New York, New York, New York 10031, United States
- Ph.D. Program in Biochemistry, The Graduate Center, City University of New York, New York, New York 10016, United States
| | - Muhamed Amin
- Laboratory of Computational Biology, National Heart, Lung and Blood, Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Gary W Brudvig
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - M R Gunner
- PhD Program in Physics, in Chemistry and in Biochemistry at the Graduate Center, City University of New York, New York, New York 10016, United States
- Department of Physics, City College of New York, New York, New York 10031, United States
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3
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Cherepanov DA, Neverov KV, Obukhov YN, Maleeva YV, Gostev FE, Shelaev IV, Aybush AV, Kritsky MS, Nadtochenko VA. Femtosecond Dynamics of Excited States of Chlorophyll Tetramer in Water-Soluble Chlorophyll-Binding Protein BoWSCP. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1580-1595. [PMID: 38105026 DOI: 10.1134/s0006297923100139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/22/2023] [Accepted: 09/22/2023] [Indexed: 12/19/2023]
Abstract
The paper reports on the absorption dynamics of chlorophyll a in a symmetric tetrameric complex of the water-soluble chlorophyll-binding protein BoWSCP. It was measured by a broadband femtosecond laser pump-probe spectroscopy within the range from 400 to 750 nm and with a time resolution of 20 fs-200 ps. When BoWSCP was excited in the region of the Soret band at a wavelength of 430 nm, nonradiative intramolecular conversion S3→S1 was observed with a characteristic time of 83 ± 9 fs. When the complex was excited in the region of the Qy band at 670 nm, relaxation transition between two excitonic states of the chlorophyll dimer was observed in the range of 105 ± 10 fs. Absorption spectra of the excited singlet states S1 and S3 of chlorophyll a were obtained. The delocalization of the excited state between exciton-coupled Chl molecules in BoWSCP tetramer changed in time and depended on the excitation energy. When BoWSCP is excited in the Soret band region, an ultrafast photochemical reaction is observed. This could result from the reduction of tryptophan in the vicinity of chlorophyll.
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Affiliation(s)
- Dmitry A Cherepanov
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia.
- Belozersky Research Institute of Physical and Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Konstantin V Neverov
- Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, 119071, Russia
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Yuriy N Obukhov
- Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, 119071, Russia
| | - Yulia V Maleeva
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Feodor E Gostev
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Ivan V Shelaev
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
- Belozersky Research Institute of Physical and Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Arseny V Aybush
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Michail S Kritsky
- Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, 119071, Russia
| | - Victor A Nadtochenko
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia.
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
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Elias E, Liguori N, Croce R. At the origin of the selectivity of the chlorophyll-binding sites in light harvesting complex II (LHCII). Int J Biol Macromol 2023:125069. [PMID: 37245759 DOI: 10.1016/j.ijbiomac.2023.125069] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 05/30/2023]
Abstract
The photosynthetic light-harvesting complexes (LHCs) are responsible for light absorption due to their pigment-binding properties. These pigments are primarily Chlorophyll (Chl) molecules of type a and b, which ensure an excellent coverage of the visible light spectrum. To date, it is unclear which factors drive the selective binding of different Chl types in the LHC binding pockets. To gain insights into this, we employed molecular dynamics simulations on LHCII binding different Chl types. From the resulting trajectories, we have calculated the binding affinities per each Chl-binding pocket using the Molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) model. To further examine the importance of the nature of the axial ligand in tuning the Chl selectivity of the binding sites, we used Density Functional Theory (DFT) calculations. The results indicate that some binding pockets have a clear Chl selectivity, and the factors governing these selectivities are identified. Other binding pockets are promiscuous, which is consistent with previous in vitro reconstitution studies. DFT calculations show that the nature of the axial ligand is not a major factor in determining the Chl binding pocket selectivity, which is instead probably controlled by the folding process.
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Affiliation(s)
- Eduard Elias
- Department of Physics and Astronomy, and Institute for Lasers, Life and Biophotonics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands
| | - Nicoletta Liguori
- Department of Physics and Astronomy, and Institute for Lasers, Life and Biophotonics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands
| | - Roberta Croce
- Department of Physics and Astronomy, and Institute for Lasers, Life and Biophotonics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands.
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Bouargalne Y, Guilbaud F, Macherel D, Delalande O, Deleu C, Le Cahérec F. Brassica napus Drought-Induced 22-kD Protein (BnD22) Acts Simultaneously as a Cysteine Protease Inhibitor and Chlorophyll-Binding Protein. PLANT & CELL PHYSIOLOGY 2023; 64:536-548. [PMID: 36905393 DOI: 10.1093/pcp/pcad016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/20/2023] [Accepted: 03/09/2023] [Indexed: 05/17/2023]
Abstract
Class II water-soluble chlorophyll proteins (WSCPs) from Brassicaceae are non-photosynthetic proteins that bind with chlorophyll (Chl) and its derivatives. The physiological function of WSCPs is still unclear, but it is assumed to be involved in stress responses, which is likely related to their Chl-binding and protease inhibition (PI) activities. Yet, the dual function and simultaneous functionality of WSCPs must still be better understood. Here, the biochemical functions of Brassica napus drought-induced 22-kDa protein (BnD22), a major WSCP expressed in B. napus leaves, were investigated using recombinant hexahistidine-tagged protein. We showed that BnD22 inhibited cysteine proteases, such as papain, but not serine proteases. BnD22 was able to bind with Chla or Chlb to form tetrameric complexes. Unexpectedly, BnD22-Chl tetramer displays higher inhibition toward cysteine proteases, indicating (i) simultaneous Chl-binding and PI activities and (ii) Chl-dependent activation of PI activity of BnD22. Moreover, the photostability of BnD22-Chl tetramer was reduced upon binding with the protease. Using three-dimensional structural modeling and molecular docking, we revealed that Chl binding favors interaction between BnD22 and proteases. Despite its Chl-binding ability, the BnD22 was not detected in chloroplasts but rather in the endoplasmic reticulum and vacuole. In addition, the C-terminal extension peptide of BnD22, which cleaved off post-translationally in vivo, was not implicated in subcellular localization. Instead, it drastically promoted the expression, solubility and stability of the recombinant protein.
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Affiliation(s)
| | - Florian Guilbaud
- IGEPP, INRAE, Institut Agro, Université Rennes, Rennes 35000, France
| | - David Macherel
- IRHS, INRAE, Institut Agro, Université Angers, Angers 49000, France
| | | | - Carole Deleu
- IGEPP, INRAE, Institut Agro, Université Rennes, Rennes 35000, France
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Fresch E, Collini E. The Role of H-Bonds in the Excited-State Properties of Multichromophoric Systems: Static and Dynamic Aspects. Molecules 2023; 28:molecules28083553. [PMID: 37110786 PMCID: PMC10141795 DOI: 10.3390/molecules28083553] [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: 03/14/2023] [Revised: 04/12/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
Given their importance, hydrogen bonds (H-bonds) have been the subject of intense investigation since their discovery. Indeed, H-bonds play a fundamental role in determining the structure, the electronic properties, and the dynamics of complex systems, including biologically relevant materials such as DNA and proteins. While H-bonds have been largely investigated for systems in their electronic ground state, fewer studies have focused on how the presence of H-bonds could affect the static and dynamic properties of electronic excited states. This review presents an overview of the more relevant progress in studying the role of H-bond interactions in modulating excited-state features in multichromophoric biomimetic complex systems. The most promising spectroscopic techniques that can be used for investigating the H-bond effects in excited states and for characterizing the ultrafast processes associated with their dynamics are briefly summarized. Then, experimental insights into the modulation of the electronic properties resulting from the presence of H-bond interactions are provided, and the role of the H-bond in tuning the excited-state dynamics and the related photophysical processes is discussed.
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Affiliation(s)
- Elisa Fresch
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Elisabetta Collini
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
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7
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Abstract
Biological pigment-protein complexes (PPCs) exhibit a remarkable ability to tune the optical properties of biological excitons (bioexcitons) through specific pigment-protein interactions. While such fine-tuning allows natural systems (e.g., photosynthetic proteins) to carry out their native functions with near-optimal performance, native function itself is often suboptimal for applications such as biofuel production or quantum technology development. This perspective offers a look at near-term prospects for the rational reoptimization of PPC bioexcitons for new functions using site-directed mutagenesis. The primary focus is on the "structure-spectrum" challenge of understanding the relationships between structural features and spectroscopic properties. While recent examples demonstrate that site-directed mutagenesis can be used to tune nearly all key bioexciton parameters (e.g., site energies, interpigment couplings, and electronic-vibrational interactions), critical challenges remain before we achieve truly rational design of bioexciton properties.
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Affiliation(s)
- Mike Reppert
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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Bouargalne Y, Raguénès-Nicol C, Guilbaud F, Cheron A, Clouet V, Deleu C, Le Cahérec F. New insights into chlorophyll-WSCP (water-soluble chlorophyll proteins) interactions : The case study of BnD22 (Brassica napus drought-induced 22 kDa). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 181:71-80. [PMID: 35452956 DOI: 10.1016/j.plaphy.2022.03.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/01/2022] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
The water-soluble chlorophyll-proteins (WSCP) of class II from Brassicaceae are non-photosynthetic proteins that bind chlorophylls (Chls) and chlorophyll derivatives. Their physiological roles, biochemical functions and mode of action are still unclear. It is assumed that the WSCPs have a protection function against Chl photodamage during stressful conditions. WSCPs are subdivided into class IIA and class IIB according to their apparent Chla/b binding ratio. Although their Chla/Chlb binding selectivity has been partly characterized, their Chl affinities are not yet precisely defined. For instance, WSCPs IIA do not show any Chl binding preference while WSCPs IIB have greater affinity to Chlb. In this study, we present a novel method for assessment of Chl binding to WSCPs based on the differences of Chl photobleaching rates in a large range of Chl/protein ratios. The protein we have chosen to study WSCP is BnD22, a WSCP IIA induced in the leaves of Brassica napus under water deficit. BnD22 formed oligomeric complexes upon binding to Chla and/or Chlb allowing a protective effect against photodamage. The binding constants indicate that BnD22 binds with high affinity the Chls and with a strong selectivity to Chla. Moreover, dependending of Chl/protein ratio upon reconstitution, two distinct binding events were detected resulting from difference of Chl stoichiometry inside oligomeric complexes.
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Affiliation(s)
- Youssef Bouargalne
- Univ Rennes 1, INRAE, Institut Agro, IGEPP - UMR 1349, 35653, Le Rheu, France
| | | | - Florian Guilbaud
- Univ Rennes 1, INRAE, Institut Agro, IGEPP - UMR 1349, 35653, Le Rheu, France
| | | | - Vanessa Clouet
- Univ Rennes 1, INRAE, Institut Agro, IGEPP - UMR 1349, 35653, Le Rheu, France
| | - Carole Deleu
- Univ Rennes 1, INRAE, Institut Agro, IGEPP - UMR 1349, 35653, Le Rheu, France
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Ciuti S, Agostini A, Barbon A, Bortolus M, Paulsen H, Di Valentin M, Carbonera D. Magnetophotoselection in the Investigation of Excitonically Coupled Chromophores: The Case of the Water-Soluble Chlorophyll Protein. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123654. [PMID: 35744779 PMCID: PMC9227413 DOI: 10.3390/molecules27123654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 12/01/2022]
Abstract
A magnetophotoselection (MPS) investigation of the photoexcited triplet state of chlorophyll a both in a frozen organic solvent and in a protein environment, provided by the water-soluble chlorophyll protein (WSCP) of Lepidium virginicum, is reported. The MPS experiment combines the photoselection achieved by exciting with linearly polarized light with the magnetic selection of electron paramagnetic resonance (EPR) spectroscopy, allowing the determination of the relative orientation of the optical transition dipole moment and the zero-field splitting tensor axes in both environments. We demonstrate the robustness of the proposed methodology for a quantitative description of the excitonic interactions among pigments. The orientation of the optical transition dipole moments determined by the EPR analysis in WSCP, identified as an appropriate model system, are in excellent agreement with those calculated in the point-dipole approximation. In addition, MPS provides information on the electronic properties of the triplet state, localized on a single chlorophyll a pigment of the protein cluster, in terms of orientation of the zero-field splitting tensor axes in the molecular frame.
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Affiliation(s)
- Susanna Ciuti
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (S.C.); (A.A.); (A.B.); (M.B.)
| | - Alessandro Agostini
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (S.C.); (A.A.); (A.B.); (M.B.)
- Biology Centre, Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 1160/31, 370 05 České Budějovice, Czech Republic
| | - Antonio Barbon
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (S.C.); (A.A.); (A.B.); (M.B.)
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (S.C.); (A.A.); (A.B.); (M.B.)
| | - Harald Paulsen
- Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Johann-Joachim Becher-Weg 7, 55128 Mainz, Germany;
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (S.C.); (A.A.); (A.B.); (M.B.)
- Correspondence: (M.D.V.); (D.C.); Tel.: +39-0498275139 (M.D.V.); +39-0498275144 (D.C.)
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (S.C.); (A.A.); (A.B.); (M.B.)
- Correspondence: (M.D.V.); (D.C.); Tel.: +39-0498275139 (M.D.V.); +39-0498275144 (D.C.)
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10
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Niklas J, Agostini A, Carbonera D, Di Valentin M, Lubitz W. Primary donor triplet states of Photosystem I and II studied by Q-band pulse ENDOR spectroscopy. PHOTOSYNTHESIS RESEARCH 2022; 152:213-234. [PMID: 35290567 PMCID: PMC9424170 DOI: 10.1007/s11120-022-00905-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/14/2022] [Indexed: 05/05/2023]
Abstract
The photoexcited triplet state of the "primary donors" in the two photosystems of oxygenic photosynthesis has been investigated by means of electron-nuclear double resonance (ENDOR) at Q-band (34 GHz). The data obtained represent the first set of 1H hyperfine coupling tensors of the 3P700 triplet state in PSI and expand the existing data set for 3P680. We achieved an extensive assignment of the observed electron-nuclear hyperfine coupling constants (hfcs) corresponding to the methine α-protons and the methyl group β-protons of the chlorophyll (Chl) macrocycle. The data clearly confirm that in both photosystems the primary donor triplet is located on one specific monomeric Chl at cryogenic temperature. In comparison to previous transient ENDOR and pulse ENDOR experiments at standard X-band (9-10 GHz), the pulse Q-band ENDOR spectra demonstrate both improved signal-to-noise ratio and increased resolution. The observed ENDOR spectra for 3P700 and 3P680 differ in terms of the intensity loss of lines from specific methyl group protons, which is explained by hindered methyl group rotation produced by binding site effects. Contact analysis of the methyl groups in the PSI crystal structure in combination with the ENDOR analysis of 3P700 suggests that the triplet is located on the Chl a' (PA) in PSI. The results also provide additional evidence for the localization of 3P680 on the accessory ChlD1 in PSII.
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Affiliation(s)
- Jens Niklas
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany.
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL, 60439, USA.
| | - Alessandro Agostini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
- Biology Centre, Institute of Plant Molecular Biology, Czech Academy of Sciences, Branišovská 31, 370 05, Ceske Budejovice, Czech Republic
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy.
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany.
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11
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Trapani M, Castriciano MA, Collini E, Bella G, Cordaro M. Supramolecular BODIPY based dimers: synthesis, computational and spectroscopic studies. Org Biomol Chem 2021; 19:8118-8127. [PMID: 34473180 DOI: 10.1039/d1ob01433a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthetic procedures for the preparation of supramolecular BODIPY dimers decorated with complementary patterns able to induce the formation of a triple hydrogen bond through mutual interactions are here reported. The BODIPY and styryl-equipped BODIPY species have been suitably functionalized in meso position with 2,6-diacetamido-4-pyridyl and 1-butyl-6-uracyl moieties. Dimers and monomers have been subjected to computational and photophysical investigations in solvent media. Various peculiarities concerning the effects of the interaction geometry on the stability of the H-bonded systems have also been investigated. The combination of modelling and experimental data provides a paradigm for improving and refining the BODIPY synthetic pathway to have chromophoric architectures with a programmable supramolecular identity. Furthermore, the possibility of assembling dimers of different dyes through H-bonds could be appealing for a systematic investigation of the principal factors affecting the dynamics of the energy migration and possibly driving coherent transfer mechanisms. Our work highlights how the chemical versatility of these dyes can be exploited to design new BODIPY-based supramolecular architectures.
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Affiliation(s)
- Mariachiara Trapani
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, V.le F. Stagno D'Alcontres 31, 98166, University of Messina, Messina, Italy
| | - Maria Angela Castriciano
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, V.le F. Stagno D'Alcontres 31, 98166, University of Messina, Messina, Italy
| | - Elisabetta Collini
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padova, Italy
| | - Giovanni Bella
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, V.le F. Stagno D'Alcontres 31, 98166, University of Messina, Messina, Italy.
| | - Massimiliano Cordaro
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, V.le F. Stagno D'Alcontres 31, 98166, University of Messina, Messina, Italy.
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12
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Guan HW, Zhu YJ, Peters J, Brea O, Himo F, Rebek J, Yu Y. Recognition of hydrophilic molecules in deep cavitand hosts with water-mediated hydrogen bonds. Chem Commun (Camb) 2021; 57:8147-8150. [PMID: 34312642 DOI: 10.1039/d1cc02505h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We describe new container host molecules - deep cavitands with benzimidazole walls and ionic feet - to recognize highly hydrophilic guest molecules in water. The aromatic surfaces of the cavity recognize hydrophobic portions of the guest while bound water molecules mediate hydrogen bonding in the complex. Spectroscopic (NMR) evidence indicates slow in/out exchange on the chemical shift timescale and thermodynamic (ITC) methods show large association constants (Ka up to 6 × 104 M-1) for complexation of small, water-soluble molecules such as THF and dioxane. Quantum chemical calculations are employed to optimize the host-guest geometries and elucidate the hydrogen bonding patterns responsible for the binding.
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Affiliation(s)
- Hua-Wei Guan
- Center for Supramolecular Chemistry & Catalysis and Department of Chemistry, College of Science, Shanghai University, 99 Shang-Da Road, Shanghai 200444, China.
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13
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Hydrophobic interaction driving the binding of soybean protein isolate and chlorophyll: Improvements to the thermal stability of chlorophyll. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106465] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Borah BP, Majumder S, Borah KD, Bhuyan J. The quest for a better understanding of ethanol coordination to magnesium and zinc porphyrin: A combined experimental and theoretical study. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Lahav Y, Noy D, Schapiro I. Spectral tuning of chlorophylls in proteins - electrostatics vs. ring deformation. Phys Chem Chem Phys 2021; 23:6544-6551. [PMID: 33690760 DOI: 10.1039/d0cp06582j] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In photosynthetic complexes, tuning of chlorophyll light-absorption spectra by the protein environment is crucial to their efficiency and robustness. Recombinant type II water soluble chlorophyll-binding proteins from Brassicaceae (WSCPs) are useful for studying spectral tuning mechanisms due to their symmetric homotetramer structure, and the ability to rigorously modify the chlorophyll's protein surroundings. Our previous comparison of the crystal structures of two WSCP homologues suggested that protein-induced chlorophyll ring deformation is the predominant spectral tuning mechanism. Here, we implement a more rigorous analysis based on hybrid quantum mechanics and molecular mechanics calculations to quantify the relative contributions of geometrical and electrostatic factors to the absorption spectra of WSCP-chlorophyll complexes. We show that when considering conformational dynamics, geometry distortions such as chlorophyll ring deformation accounts for about one-third of the spectral shift, whereas the direct polarization of the electron density accounts for the remaining two-thirds. From a practical perspective, protein electrostatics is easier to manipulate than chlorophyll conformations, thus, it may be more readily implemented in designing artificial protein-chlorophyll complexes.
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Affiliation(s)
- Yigal Lahav
- Fritz Haber Centre for Molecular Dynamics Research, Institute of Chemistry, Hebrew University of Jerusalem, Israel.
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16
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Fresch E, Peruffo N, Trapani M, Cordaro M, Bella G, Castriciano MA, Collini E. The effect of hydrogen bonds on the ultrafast relaxation dynamics of a BODIPY dimer. J Chem Phys 2021; 154:084201. [PMID: 33639732 DOI: 10.1063/5.0038242] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The influence of hydrogen bonds (H-bonds) in the structure, dynamics, and functionality of biological and artificial complex systems is the subject of intense investigation. In this broad context, particular attention has recently been focused on the ultrafast H-bond dependent dynamical properties in the electronic excited state because of their potentially dramatic consequences on the mechanism, dynamics, and efficiency of photochemical reactions and photophysical processes of crucial importance for life and technology. Excited-state H-bond dynamics generally occur on ultrafast time scales of hundreds of femtoseconds or less, making the characterization of associated mechanisms particularly challenging with conventional time-resolved techniques. Here, 2D electronic spectroscopy is exploited to shed light on this still largely unexplored dynamic mechanism. An H-bonded molecular dimer prepared by self-assembly of two boron-dipyrromethene dyes has been specifically designed and synthesized for this aim. The obtained results confirm that upon formation of H-bonds and the dimer, a new ultrafast relaxation channel is activated in the ultrafast dynamics, mediated by the vibrational motions of the hydrogen donor and acceptor groups. This relaxation channel also involves, beyond intra-molecular relaxations, an inter-molecular transfer process. This is particularly significant considering the long distance between the centers of mass of the two molecules. These findings suggest that the design of H-bonded structures is a particularly powerful tool to drive the ultrafast dynamics in complex materials.
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Affiliation(s)
- Elisa Fresch
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padova, Italy
| | - Nicola Peruffo
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padova, Italy
| | - Mariachiara Trapani
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, V.le F. Stagno D'Alcontres 31, 98166 Messina, Italy
| | - Massimiliano Cordaro
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina, V.le F. Stagno D'Alcontres 31, 98166 Messina, Italy
| | - Giovanni Bella
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina, V.le F. Stagno D'Alcontres 31, 98166 Messina, Italy
| | - Maria Angela Castriciano
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, V.le F. Stagno D'Alcontres 31, 98166 Messina, Italy
| | - Elisabetta Collini
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padova, Italy
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17
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Sirohiwal A, Neese F, Pantazis DA. Protein Matrix Control of Reaction Center Excitation in Photosystem II. J Am Chem Soc 2020; 142:18174-18190. [PMID: 33034453 PMCID: PMC7582616 DOI: 10.1021/jacs.0c08526] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Indexed: 02/06/2023]
Abstract
Photosystem II (PSII) is a multisubunit pigment-protein complex that uses light-induced charge separation to power oxygenic photosynthesis. Its reaction center chromophores, where the charge transfer cascade is initiated, are arranged symmetrically along the D1 and D2 core polypeptides and comprise four chlorophyll (PD1, PD2, ChlD1, ChlD2) and two pheophytin molecules (PheoD1 and PheoD2). Evolution favored productive electron transfer only via the D1 branch, with the precise nature of primary excitation and the factors that control asymmetric charge transfer remaining under investigation. Here we present a detailed atomistic description for both. We combine large-scale simulations of membrane-embedded PSII with high-level quantum-mechanics/molecular-mechanics (QM/MM) calculations of individual and coupled reaction center chromophores to describe reaction center excited states. We employ both range-separated time-dependent density functional theory and the recently developed domain based local pair natural orbital (DLPNO) implementation of the similarity transformed equation of motion coupled cluster theory with single and double excitations (STEOM-CCSD), the first coupled cluster QM/MM calculations of the reaction center. We find that the protein matrix is exclusively responsible for both transverse (chlorophylls versus pheophytins) and lateral (D1 versus D2 branch) excitation asymmetry, making ChlD1 the chromophore with the lowest site energy. Multipigment calculations show that the protein matrix renders the ChlD1 → PheoD1 charge-transfer the lowest energy excitation globally within the reaction center, lower than any pigment-centered local excitation. Remarkably, no low-energy charge transfer states are located within the "special pair" PD1-PD2, which is therefore excluded as the site of initial charge separation in PSII. Finally, molecular dynamics simulations suggest that modulation of the electrostatic environment due to protein conformational flexibility enables direct excitation of low-lying charge transfer states by far-red light.
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Affiliation(s)
- Abhishek Sirohiwal
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
- Fakultät
für Chemie und Biochemie, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Frank Neese
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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18
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Sirohiwal A, Berraud-Pache R, Neese F, Izsák R, Pantazis DA. Accurate Computation of the Absorption Spectrum of Chlorophyll a with Pair Natural Orbital Coupled Cluster Methods. J Phys Chem B 2020; 124:8761-8771. [PMID: 32930590 PMCID: PMC7584356 DOI: 10.1021/acs.jpcb.0c05761] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
The
ability to accurately compute low-energy excited states of
chlorophylls is critically important for understanding the vital roles
they play in light harvesting, energy transfer, and photosynthetic
charge separation. The challenge for quantum chemical methods arises
both from the intrinsic complexity of the electronic structure problem
and, in the case of biological models, from the need to account for
protein–pigment interactions. In this work, we report electronic
structure calculations of unprecedented accuracy for the low-energy
excited states in the Q and B bands of chlorophyll a. This is achieved by using the newly developed domain-based local
pair natural orbital (DLPNO) implementation of the similarity transformed
equation of motion coupled cluster theory with single and double excitations
(STEOM-CCSD) in combination with sufficiently large and flexible basis
sets. The results of our DLPNO–STEOM-CCSD calculations are
compared with more approximate approaches. The results demonstrate
that, in contrast to time-dependent density functional theory, the
DLPNO–STEOM-CCSD method provides a balanced performance for
both absorption bands. In addition to vertical excitation energies,
we have calculated the vibronic spectrum for the Q and B bands through
a combination of DLPNO–STEOM-CCSD and ground-state density
functional theory frequency calculations. These results serve as a
basis for comparison with gas-phase experiments.
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Affiliation(s)
- Abhishek Sirohiwal
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.,Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Romain Berraud-Pache
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Róbert Izsák
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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19
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Girr P, Kilper J, Pohland AC, Paulsen H. The pigment binding behaviour of water-soluble chlorophyll protein (WSCP). Photochem Photobiol Sci 2020; 19:695-712. [PMID: 32338263 DOI: 10.1039/d0pp00043d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/17/2020] [Indexed: 12/17/2023]
Abstract
Water-soluble chlorophyll proteins (WSCPs) are homotetrameric proteins that bind four chlorophyll (Chl) molecules in identical binding sites, which makes WSCPs a good model to study protein-pigment interactions. In a previous study, we described preferential binding of Chl a or Chl b in various WSCP versions. Chl b binding is preferred when a hydrogen bond can be formed between the C7 formyl of the chlorin macrocycle and the protein, whereas Chl a is preferred when Chl b binding is sterically unfavorable. Here, we determined the binding affinities and kinetics of various WSCP versions not only for Chl a/b, but also for chlorophyllide (Chlide) a/b and pheophytin (Pheo) a/b. Altered KD values are responsible for the Chl a/b selectivity in WSCP whereas differences in the reaction kinetics are neglectable in explaining different Chl a/b preferences. WSCP binds both Chlide and Pheo with a lower affinity than Chl, which indicates the importance of the phytol chain and the central Mg2+ ion as interaction sites between WSCP and pigment. Pheophorbide (Pheoide), lacking both the phytol chain and the central Mg2+ ion, can only be bound as Pheoide b to a WSCP that has a higher affinity for Chl b than Chl a, which underlines the impact of the C7 formyl-protein interaction. Moreover, WSCP was able to bind protochlorophyllide and Mg-protoporphyrin IX, which suggests that neither the size of the π electron system of the macrocycle nor the presence of a fifth ring at the macrocycle notably affect the binding to WSCP. WSCP also binds heme to form a tetrameric complex, suggesting that heme is bound in the Chl-binding site.
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Affiliation(s)
- Philipp Girr
- Institute of Molecular Physiology, Johannes Gutenberg-University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany
| | - Jessica Kilper
- Institute of Molecular Physiology, Johannes Gutenberg-University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany
| | - Anne-Christin Pohland
- Institute of Molecular Physiology, Johannes Gutenberg-University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany
| | - Harald Paulsen
- Institute of Molecular Physiology, Johannes Gutenberg-University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany.
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20
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Fresch E, Meneghin E, Agostini A, Paulsen H, Carbonera D, Collini E. How the Protein Environment Can Tune the Energy, the Coupling, and the Ultrafast Dynamics of Interacting Chlorophylls: The Example of the Water-Soluble Chlorophyll Protein. J Phys Chem Lett 2020; 11:1059-1067. [PMID: 31952446 PMCID: PMC7995254 DOI: 10.1021/acs.jpclett.9b03628] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The interplay between active molecules and the protein environment in light-harvesting complexes tunes the photophysics and the dynamical properties of pigment-protein complexes in a subtle way, which is not fully understood. Here we characterized the photophysics and the ultrafast dynamics of four variants of the water-soluble chlorophyll protein (WSCP) as an ideal model system to study the behavior of strongly interacting chlorophylls. We found that when coordinated by the WSCP protein, the presence of the formyl group in chlorophyll b replacing the methyl group in chlorophyll a strongly affects the exciton energy and the dynamics of the system, opening up the possibility of tuning the photophysics and the transport properties of multichromophores by engineering specific interactions with the surroundings.
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Affiliation(s)
- Elisa Fresch
- Department
of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padua, Italy
| | - Elena Meneghin
- Department
of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padua, Italy
| | - Alessandro Agostini
- Department
of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padua, Italy
- Institute
of Molecular Physiology, Johannes Gutenberg-University, Johannes-von-Müller-Weg 6, 55128 Mainz, Germany
| | - Harald Paulsen
- Institute
of Molecular Physiology, Johannes Gutenberg-University, Johannes-von-Müller-Weg 6, 55128 Mainz, Germany
| | - Donatella Carbonera
- Department
of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padua, Italy
| | - Elisabetta Collini
- Department
of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padua, Italy
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