Photoprotection and triplet energy transfer in higher plants: the role of electronic and nuclear fluctuations

Cupellini, Lorenzo; Jurinovich, Sandro; Prandi, Ingrid Guarnetti; Caprasecca, Stefano; Mennucci, Benedetta

doi:10.1039/c6cp01437b

Cited by 22 publications

(24 citation statements)

References 59 publications

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“…Triplet-triplet energy transfer from chlorophylls to carotenoids is mediated by Dexter mechanism (Dexter, 1953), which needs overlap between the electron clouds of the donor and acceptor. When distance or orientation of carotenoid and chlorophyll is changed, the capability of carotenoids to quench excitation energy of triplet chlorophylls is diminished (Cupellini et al, 2016). Under such conditions, when O 2 is in the proximity of triplet chlorophyll, the transfer of excitation energy from triplet chlorophyll to O 2 forms 1 O 2 .…”

Section: High Lightmentioning

confidence: 99%

Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress

2016

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The effect of various abiotic stresses on photosynthetic apparatus is inevitably associated with formation of harmful reactive oxygen species (ROS). In this review, recent progress on ROS production by photosystem II (PSII) as a response to high light and high temperature is overviewed. Under high light, ROS production is unavoidably associated with energy transfer and electron transport in PSII. Singlet oxygen is produced by the energy transfer form triplet chlorophyll to molecular oxygen formed by the intersystem crossing from singlet chlorophyll in the PSII antennae complex or the recombination of the charge separated radical pair in the PSII reaction center. Apart to triplet chlorophyll, triplet carbonyl formed by lipid peroxidation transfers energy to molecular oxygen forming singlet oxygen. On the PSII electron acceptor side, electron leakage to molecular oxygen forms superoxide anion radical which dismutes to hydrogen peroxide which is reduced by the non-heme iron to hydroxyl radical. On the PSII electron donor side, incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. Under high temperature, dark production of singlet oxygen results from lipid peroxidation initiated by lipoxygenase, whereas incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. The understanding of molecular basis for ROS production by PSII provides new insight into how plants survive under adverse environmental conditions.

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Section: High Lightmentioning

confidence: 99%

Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress

2016

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“…Investigating the role of TET in photoprotection is thus more complicated, as the relevant coupling term cannot be expressed with the approximation presented in the previous section. Atomistic investigations of TET in photoprotection [120,121] have thus employed quantum chemical methods, in conjunction to a diabatization scheme called Fragment Spin Difference [122] to compute the TET coupling. One of the main findings of these atomistic simulations is that TET rates can be strongly enhanced by geometrical fluctuations [121], due to the steep distance dependence of Dexter's mechanism.…”

Section: From the Lh Function To Its Photoregulationmentioning

confidence: 99%

Successes & challenges in the atomistic modeling of light-harvesting and its photoregulation

Cupellini

Bondanza

Nottoli

et al. 2020

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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Light-harvesting is a crucial step of photosynthesis. Its mechanisms and related energetics have been revealed by a combination of experimental investigations and theoretical modeling. The success of theoretical modeling is largely due to the application of atomistic descriptions combining quantum chemistry, classical models and molecular dynamics techniques. Besides the important achievements obtained so far, a complete and quantitative understanding of how the many different light-harvesting complexes exploit their structural specificity is still missing. Moreover, many questions remain unanswered regarding the mechanisms through which light-harvesting is regulated in response to variable light conditions. Here we show that, in both fields, a major role will be played once more by atomistic descriptions, possibly generalized to tackle the numerous time and space scales on which the regulation takes place: going from the ultrafast electronic excitation of the multichromophoric aggregate, through the subsequent conformational changes in the embedding protein, up to the interaction between proteins.

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“…Indeed, different MD-based studies have shown that structural fluctuations significantly enhance TEET dynamics, which can be explained on the basis of the tails observed in the coupling distributions. 98,100,101 Regarding SEET couplings, in systems where the D/A molecules are held in a relatively rigid conformation, for example, the chlorophylls in the CP29 complex, the fluctuations display a more Gaussian distribution, as shown in Figure 4c, and a reasonable estimate of the rate can often be achieved by computing the coupling from a static structure. For example, a number of studies have been able to describe the light-harvesting properties of photosynthetic complexes based on static structures, although others adopt MD-averaged values.…”

Section: The Role Of Fluctuationsmentioning

confidence: 99%

“…83 (b) triplet-triplet energy transfer (TEET) coupling between two adenines in a polyA-polyT DNA sequence, 98 (c) SEET coupling between chlorophylls a603 and a609 in the CP29 photosynthetic complex, 79 (d) TEET coupling between chlorophyll a603 and violaxanthin in the CP29 photosynthetic complex. 101 In FRET systems where conformational transitions and fluorophore orientational dynamics can drastically change the mutual distance and orientation between the D/A chromophores, MD simulations are particularly useful in disentangling dynamic and static coupling fluctuations in the prediction of EET efficiencies. 17,19,38 If the coupling fluctuations along the trajectory are fast compared with the donor excited-state decay (dynamic averaging regime), the efficiency can be calculated using the averaged rate constant:…”

Section: The Role Of Fluctuationsmentioning

confidence: 99%

“…When dealing with triplet states, the difficulty in obtaining triplet absorption spectra can be overcome by employing spectral parameters for singlet absorption, and adjusting the excitation energy to match the triplet energy. 101,105 Particular caution should be used when determining spectral FIGURE 5 Spectral overlap between a carotenoid donor and a bacteriochlorophyll acceptor. The filled curves represent the densities of states f A and f D , whilst the dashed line represents the value of the spectral overlap J as a function of the vertical excitation energy of the acceptor, in logarithmic scale overlaps from experimental spectra, because their lineshape contains contributions from both homogeneous and inhomogeneous broadening.…”

Section: From the Fcwd Factor To The Spectral Overlapmentioning

confidence: 99%

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Electronic energy transfer in biomacromolecules

Cupellini

Corbella

Mennucci

et al. 2018

WIREs Comput Mol Sci

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Electronic energy transfer is widely used as a molecular ruler to interrogate the structure of biomacromolecules, and performs a key task in photosynthesis by transferring collected energy through specialized pigment–protein complexes. Förster theory, introduced over 70 years ago, allows linking transfer rates to simple structural and spectroscopic properties of the energy‐transferring molecules. In biosystems, however, significant deviations from Förster behavior often arise due to breakdown of the ideal dipole approximation, dielectric screening effects due to the biological environment, or departure from the weak‐coupling regime. In this review, we provide a concise overview of advances in simulations of energy transfer in biomacromolecules that allow overcoming the main limitations of Förster theory. We first discuss advances in quantum chemical methods to compute electronic couplings, their extension to multiscale formulations to include screening effects, and strategies to treat the interplay between coupling fluctuations and energy transfer dynamics. We then examine the spectral overlap term, and how this quantity can be estimated from simulations of the spectral density of exciton–phonon coupling. Finally, we discuss rate theories that can describe energy transfers in situations where strong coupling leads to delocalized excitions, a common situation found in closely packed multichromophoric systems such as photosynthetic complexes and nucleic acids. This article is categorized under: Structure and Mechanism > Computational Biochemistry and Biophysics Theoretical and Physical Chemistry > Spectroscopy

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Photoprotection and triplet energy transfer in higher plants: the role of electronic and nuclear fluctuations

Abstract: Abstract-The quenching of Chlorophyll triplets by triplet energy transfer (TET) to carotenoids is one of the photoprotection strategies in photosynthetic organisms, and prevents singlet oxygen formation.

Cited by 22 publications

References 59 publications

Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress

Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress

Successes & challenges in the atomistic modeling of light-harvesting and its photoregulation

Electronic energy transfer in biomacromolecules

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