Energy landscape of the intact and destabilized FMO antennas from C. tepidum and the L122Q mutant: Low temperature spectroscopy and modeling study

Khmelnitskiy, Anton; Kell, Adam; Reinot, T.; Saer, Rafael G.; Blankenship, Robert E.; Jankowiak, Ryszard

doi:10.1016/j.bbabio.2017.11.008

Cited by 9 publications

(59 citation statements)

References 49 publications

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“…Thus, it is likely that BChls 1 and 6 collect excitation from baseplate pigments, implying the existence of one or two (depending on modelling studies) relaxation pathways within a monomer [9,14,26,27]. A single pathway with BChl 6 being the highest energy pigment is consistent with recent modelling studies of intact and intact/destabilized mixture FMO samples, where simultaneous fits of multiple optical spectra suggested that BChl 6 has the highest site energy followed by similar site energies of BChls 1 and 2 [24].…”

Section: Introductionsupporting

confidence: 82%

“…(b) BChls 1 -8 contributions to the calculated absorption spectrum shown in (a). Adapted from [24]. (Online version in colour.)…”

Section: Discussionmentioning

confidence: 99%

“…Next, expanding on the above results, low-temperature optical spectra for the entire 24-pigment FMO trimer are modelled using a combination of non-Markovian Redfield and generalized Förster theories [24]. The results are shown in figure 7 along with spectral contributions of the eight BChls.…”

Section: Rate Equationsmentioning

confidence: 99%

“…Because of the orientation of FMO in relation to the RC, it was suggested that BChl 8 is the entry point of excitations from the chlorosome/baseplate system, with BChl 3 being the energy sink that transfers this energy to the P840 dimer of the RC [18,21]. However, the site energy of BChl 8 near 803 -804 nm (12 453 -12 438 cm 21 ) and very weak coupling with other pigments most probably excludes such a scenario [20,[22][23][24]. Moreover, the calculations of Ritschel et al [25] showed that a relatively faster transfer is observed when initialization at BChls 1 or 6 is considered.…”

Section: Introductionmentioning

confidence: 99%

“…This simple model included both frequencydependent EET rate distributions and burning following EET and provided reasonable fits of various optical spectra including resonant and non-resonant holes in the case of the FMO complex. In subsequent works [23,24], briefly discussed below, a more advanced model that incorporated excitonic interactions was used to further demonstrate that the low-energy 825 nm band cannot be properly described by a single excitonic state.…”

Section: Introductionmentioning

confidence: 99%

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On uncorrelated inter-monomer Förster energy transfer in Fenna–Matthews–Olson complexes

Kell

Khmelnitskiy

Reinot

et al. 2019

J. R. Soc. Interface.

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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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Section: Introductionsupporting

confidence: 82%

“…(b) BChls 1 -8 contributions to the calculated absorption spectrum shown in (a). Adapted from [24]. (Online version in colour.)…”

Section: Discussionmentioning

confidence: 99%

Section: Rate Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On uncorrelated inter-monomer Förster energy transfer in Fenna–Matthews–Olson complexes

Kell

Khmelnitskiy

Reinot

et al. 2019

J. R. Soc. Interface.

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Excitonic Energy Landscape of the Y16F Mutant of the Chlorobium tepidum Fenna–Matthews–Olson (FMO) Complex: High Resolution Spectroscopic and Modeling Studies

et al. 2018

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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 (Sub and Sub) 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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Mixed Upper Exciton State of the Special Pair in Bacterial Reaction Centers

2019

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Excitonic interactions between two closely separated bacteriochlorophyll a molecules (BChls) in the special pair of the reaction center (RC) of purple bacteria determine the positions and relative oscillator strengths of its two excitonic components. While the absorption of the lower excitonic band is well-defined, the position and the intensity of the upper excitonic band (PY+ ) are still under debate. Recent 77 K two-dimensional electronic spectroscopy data on Rba. capsulatus suggested that the PY+ component absorbs at ∼840 nm, i.e., at a significantly lower energy than previously suggested. In the present work, we argue that the PY+ state is mixed with the excited states of the accessory BChls (B*/P Y+) leading to excitons contributing to the 785–825 nm spectral region which is consistent with previously published data. This conclusion is based on hole-burning/linear dichroism data and modeling studies of the excitonic structure of the RC using a non-Markovian reduced density matrix approach.

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Energy landscape of the intact and destabilized FMO antennas from C. tepidum and the L122Q mutant: Low temperature spectroscopy and modeling study

Cited by 9 publications

References 49 publications

On uncorrelated inter-monomer Förster energy transfer in Fenna–Matthews–Olson complexes

On uncorrelated inter-monomer Förster energy transfer in Fenna–Matthews–Olson complexes

Excitonic Energy Landscape of the Y16F Mutant of the Chlorobium tepidum Fenna–Matthews–Olson (FMO) Complex: High Resolution Spectroscopic and Modeling Studies

Mixed Upper Exciton State of the Special Pair in Bacterial Reaction Centers

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