A Structure-Based Model of Energy Transfer Reveals the Principles of Light Harvesting in Photosystem II Supercomplexes

Bennett, Doran I. G.; Amarnath, Kapil; Fleming, Graham R.

doi:10.1021/ja403685a

Cited by 120 publications

(214 citation statements)

References 54 publications

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“…Additionally, we assume the coupling constants are identical across all sites g nk = g k . Motivated by its relevance in quantum dots and light harvesting systems, we choose a super-Ohmic spectral density, [25][26][27] …”

Section: Theorymentioning

confidence: 99%

Coherent quantum transport in disordered systems: A unified polaron treatment of hopping and band-like transport

Lee

Moix

Cao

2015

The Journal of Chemical Physics

103

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Quantum transport in disordered systems is studied using a polaron-based master equation. The polaron approach is capable of bridging the results from the coherent band-like transport regime governed by the Redfield equation to incoherent hopping transport in the classical regime. A non-monotonic dependence of the diffusion coefficient is observed both as a function of temperature and system-phonon coupling strength. In the band-like transport regime, the diffusion coefficient is shown to be linearly proportional to the system-phonon coupling strength and vanishes at zero coupling due to Anderson localization. In the opposite classical hopping regime, we correctly recover the dynamics described by the Fermi's Golden Rule and establish that the scaling of the diffusion coefficient depends on the phonon bath relaxation time. In both the hopping and band-like transport regimes, it is demonstrated that at low temperature, the zero-point fluctuations of the bath lead to non-zero transport rates and hence a finite diffusion constant. Application to rubrene and other organic semiconductor materials shows a good agreement with experimental mobility data. C 2015 AIP Publishing LLC. [http://dx

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Section: Theorymentioning

confidence: 99%

Coherent quantum transport in disordered systems: A unified polaron treatment of hopping and band-like transport

Lee

Moix

Cao

2015

The Journal of Chemical Physics

103

View full text Add to dashboard Cite

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“…A typical radiative rate of k f = 16 ns was assumed to be constant and the same between different samples. 24,25 The detection efficiency can only be estimated (about 5%) but stays constant between two measurements. Systematic errors can arise from changes in the radiative rate k f and misfits of the decay components including missing very fast decay processes (<5 ps) can also lead to errors in the calculated absorption cross section.…”

Section: Relative Absorption Cross Sectionmentioning

confidence: 99%

Photophysics in single light-harvesting complexes II: from micelle to native nanodisks

et al. 2016

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Most photosynthetic pigment-protein complexes of algae and higher plants are integral membrane proteins and are thus usually isolated in the presence of detergent to provide a hydrophobic interface and prevent aggregation. It was recently shown that the styrene maleic acid (SMA) copolymer can be used instead to solubilize and isolate protein complexes with their native lipid environment into nanodisk particles. We isolated LHCII complexes in SMA and compared their photophysics with trimeric LHCII complexes in β-DM detergent micelles to understand the effect of the native environment on the function of light-harvesting antennae. The triplet state kinetics and the calculated relative absorption cross section of single complexes indicate the successful isolation of trimeric complexes in SMA nanodisks, confirming the trimeric structure as the likely native configuration. The survival time of complexes before they photobleach is increased in SMA compared to detergent which might be explained by a stabilizing effect of the co-purified lipids in nanodisks. We furthermore find an unquenched fluorescence lifetime of 3.5 ns for LHCII in SMA nanodisks which coincides with detergent isolated complexes and notably differs from 2 ns typically found in native thylakoid structures. A large dynamic range of partially quenched complexes both in detergent micelles and lipid nanodisks is demonstrated by correlating the fluorescence lifetime with the intensity and likely reflects the conformational freedom of these complexes. This further supports the hypothesis that fluorescence intermittency is an intrinsic property of LHCII that may be involved in excess energy dissipation in native light-harvesting.

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“…The array of protective dissipative processes triggered in various organisms under light stress, referred to as nonphotochemical quenching (NPQ) is also a major focus [10][11][12]. The location of the chlorophyll excited states that are lowest in energy is a key factor in our understanding of the energy transfer kinetics, because these states play a prominent role in determining the flow of excitation energy [13][14][15][16]. Each chlorophyll molecule is located in a unique binding site in its protein, and the pigment-protein interactions at these binding sites dictate the transition energy, or site energy, of each pigment.…”

Section: Introductionmentioning

confidence: 99%

The lowest-energy chlorophyll of photosystem II is adjacent to the peripheral antenna: Emitting states of CP47 assigned via circularly polarized luminescence

Hall

Renger

Müh

et al. 2016

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The identification of low-energy chlorophyll pigments in photosystem II (PSII) is critical to our understanding of the kinetics and mechanism of this important enzyme. We report parallel circular dichroism (CD) and circularly polarized luminescence (CPL) measurements at liquid helium temperatures of the proximal antenna protein CP47. This assembly hosts the lowest-energy chlorophylls in PSII, responsible for the well-known "F695" fluorescence band of thylakoids and PSII core complexes. Our new spectra enable a clear identification of the lowest-energy exciton state of CP47. This state exhibits a small but measurable excitonic delocalization, as predicated by its CD and CPL. Using structure-based simulations incorporating the new spectra, we propose a revised set of site energies for the 16 chlorophylls of CP47. The significant difference from previous analyses is that the lowest-energy pigment is assigned as Chl 612 (alternately numbered Chl 11). The new assignment is readily reconciled with the large number of experimental observations in the literature, while the most common previous assignment for the lowest energy pigment, Chl 627(29), is shown to be inconsistent with CD and CPL results. Chl 612(11) is near the peripheral light-harvesting system in higher plants, in a lumen-exposed region of the thylakoid membrane. The low-energy pigment is also near a recently proposed binding site of the PsbS protein. This result consequently has significant implications for our understanding of the kinetics and regulation of energy transfer in PSII.

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A Structure-Based Model of Energy Transfer Reveals the Principles of Light Harvesting in Photosystem II Supercomplexes

Cited by 120 publications

References 54 publications

Coherent quantum transport in disordered systems: A unified polaron treatment of hopping and band-like transport

Coherent quantum transport in disordered systems: A unified polaron treatment of hopping and band-like transport

Photophysics in single light-harvesting complexes II: from micelle to native nanodisks

The lowest-energy chlorophyll of photosystem II is adjacent to the peripheral antenna: Emitting states of CP47 assigned via circularly polarized luminescence

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