Photosynthetic Light Harvesting

Mirkovic, Tihana; Scholes, Gregory D.

doi:10.1007/978-1-4939-1468-5_17

Cited by 4 publications

(6 citation statements)

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“…Even though the intensity and spectral quality of light can be vastly different on temporal and spatial scales, the light-harvesting machinery of photosynthetic organisms has evolved adaptation mechanisms that allow these organisms to thrive in diverse environments. − For example, plant canopies provide a vertical gradient of sunlight, attenuating the intensity of visible light by a factor of up to 100 as it passes from the top of the canopy to the shade beneath (Figure a). For algae growing in oceans or lakes, water plays an important role in filtering specific wavelengths of light. , Short wavelengths of the visible light spectrum, such as blue and green, penetrate the water much farther than red light does.…”

Section: Spectral Composition Of Light and The Pigmentsmentioning

confidence: 99%

“…Copyright 2005 Pearson Education, Inc. (c) Absorption spectra of photosynthetic pigments utilized in light harvesting. , (d) Chemical structures of the chlorophyll, carotenoid, and phycobilin pigments. Adapted with permission from ref . Copyright 2015 Springer.…”

Section: Spectral Composition Of Light and The Pigmentsmentioning

confidence: 99%

“…Shorter wavelengths of light are absorbed by peripheral antenna complexes, followed by energy-transfer processes to the lower-energy pigments located closer to the reaction center . Adapted with permission from ref . Copyright 2015 Springer.…”

Section: Physical Principles Of Antenna Architecturementioning

confidence: 99%

“…(c) Illustration of the spectral overlap and the calculated overlap integral for an acceptor (chlorophyll a )/donor [phycoerythrin 545 (PE545)] pair. Adapted with permission from ref . Copyright 2015 Springer.…”

Section: Mechanism Of Förster Excitation Energy Transfermentioning

confidence: 99%

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Light Absorption and Energy Transfer in the Antenna Complexes of Photosynthetic Organisms

et al. 2016

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The process of photosynthesis is initiated by the capture of sunlight by a network of light-absorbing molecules (chromophores), which are also responsible for the subsequent funneling of the excitation energy to the reaction centers. Through evolution, genetic drift, and speciation, photosynthetic organisms have discovered many solutions for light harvesting. In this review, we describe the underlying photophysical principles by which this energy is absorbed, as well as the mechanisms of electronic excitation energy transfer (EET). First, optical properties of the individual pigment chromophores present in light-harvesting antenna complexes are introduced, and then we examine the collective behavior of pigment-pigment and pigment-protein interactions. The description of energy transfer, in particular multichromophoric antenna structures, is shown to vary depending on the spatial and energetic landscape, which dictates the relative coupling strength between constituent pigment molecules. In the latter half of the article, we focus on the light-harvesting complexes of purple bacteria as a model to illustrate the present understanding of the synergetic effects leading to EET optimization of light-harvesting antenna systems while exploring the structure and function of the integral chromophores. We end this review with a brief overview of the energy-transfer dynamics and pathways in the light-harvesting antennas of various photosynthetic organisms.

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Section: Spectral Composition Of Light and The Pigmentsmentioning

confidence: 99%

Section: Spectral Composition Of Light and The Pigmentsmentioning

confidence: 99%

Section: Physical Principles Of Antenna Architecturementioning

confidence: 99%

Section: Mechanism Of Förster Excitation Energy Transfermentioning

confidence: 99%

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Light Absorption and Energy Transfer in the Antenna Complexes of Photosynthetic Organisms

et al. 2016

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“…Moreover, discoidal structures provide advantages in seagrass‐dominated environments, as they maximize nutrient absorption from below and offer maximal exposure surfaces to light (Hallock et al ., 1991). On the contrary, peneroplids, with spiral to flabelliform growth patterns, host red‐algal symbionts whose pigments show higher light absorbance at longer wavelengths than those of green algae and dinoflagellates (Wangpraseurt et al ., 2014; Mirkovic & Scholes, 2015) and hence can thrive in lower light conditions (for example, close to the rhizome beneath the blades). On the other hand, diatom‐bearing large rotaliids and alveolinids use a wide light‐spectrum and therefore are less specialized to particular photic environments (euryphotic); thus, they are recognized as seagrass dwellers, beneath the leaf canopy, but also in deeper environments with equivalent, poor‐light conditions (Pomar et al ., 2017).…”

Section: Discussionmentioning

confidence: 99%

Seagrass development in terrigenous‐influenced inner ramp settings during the middle Eocene (Urbasa–Andia Plateau, Western Pyrenees, North Spain)

Baceta

Mateu‐Vicens

2021

Sedimentology

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Since their first occurrence in the late Cretaceous, seagrasses have played a major role in carbonate production and sedimentation across shallow‐water and nearshore environments, sustaining a prolific carbonate factory and contributing to sediment accumulation through the combination of baffling and trapping effects. Most reported Palaeogene seagrass occurrences developed in oligo−mesotrophic shallow warm‐water habitats and are characterized by distinct associations of small and larger benthic foraminifers adapted to low terrigenous influence. This study describes a number of seagrass episodes interbedded in the Bartonian (middle Eocene) of San Fausto–Lazkua area (Navarra region, North Spain), within a nearshore to inner‐ramp succession that, in spite of being deposited under general transgressive conditions, was highly influenced by terrigenous supply from the adjacent land. Up to twelve different seagrass bed intervals occur interbedded in a cyclical manner with high‐energy nearshore siliciclastics and inner ramp bioclastic carbonates rich in mesophotic−oligophotic foraminifers and heterozoan biota (red algae, echinoderms, bryozoans). Seagrass deposits exhibit typical unsorted textures, abundant bioturbation and moderate to high terrigenous content, and comprise a characteristic skeletal association of epiphytic foraminifers, red algae and, most particularly, of abundant encrusting acervulinids, commonly with distinct hooked and tubular growth forms. This abundance of suspension‐feeders relative to autotrophs and mixotrophs may be indicative of temperate waters, although the taxonomic diversity of the foraminiferal assemblages in both seagrass and non‐seagrass embedding deposits supports the interpretation of shallow, warm‐water conditions. The studied seagrass deposits provide evidence that high siliciclastic supply and associated nutrient input may determine the occurrence of temperate‐like seagrass deposits in warm‐water settings, analogous to extensive heterozoan carbonate production in modern shallow‐tropical environments. Thus, the identification and correct interpretation of past seagrass‐vegetated environments are crucial for reconstructing palaeoecological conditions in ancient shallow‐marine environments. Therefore, in comparison with carbonate‐dominated environments, the mixed terrigenous−carbonate seagrass deposits are volumetrically less important, presenting a more irregular, patchy distribution, and a skeletal assemblage dominated by heterotrophs, regardless of the water temperature.

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Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model

Sisto

Stross

Kamp

et al. 2017

Phys. Chem. Chem. Phys.

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We recently outlined an efficient multi-tiered parallel ab initio excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground and excited state energies and gradients of large supramolecular complexes in atomistic detail - enabling us to undertake non-adiabatic simulations which explicitly account for the coupled anharmonic vibrational motion of all the constituent atoms in a supramolecular system. Here we apply that framework to the 27 coupled bacterio-chlorophyll-a chromophores which make up the LH2 complex, using it to compute an on-the-fly nonadiabatic surface-hopping (SH) trajectory of electronically excited LH2. Part one of this article is focussed on calibrating our ab initio exciton Hamiltonian using two key parameters: a shift δ, which corrects for the error in TDDFT vertical excitation energies; and an effective dielectric constant ε, which describes the average screening of the transition-dipole coupling between chromophores. Using snapshots obtained from equilibrium molecular dynamics simulations (MD) of LH2, we tune the values of both δ and ε through fitting to the thermally broadened experimental absorption spectrum, giving a linear absorption spectrum that agrees reasonably well with experiment. In part two of this article, we construct a time-resolved picture of the coupled vibrational and excitation energy transfer (EET) dynamics in the sub-picosecond regime following photo-excitation. Assuming Franck-Condon excitation of a narrow eigenstate band centred at 800 nm, we use surface hopping to follow a single nonadiabatic dynamics trajectory within the full eigenstate manifold. Consistent with experimental data, this trajectory gives timescales for B800→B850 population transfer (τ) between 650-1050 fs, and B800 population decay (τ) between 10-50 fs. The dynamical picture that emerges is one of rapidly fluctuating LH2 eigenstates that are delocalized over multiple chromophores and undergo frequent crossing on a femtosecond timescale as a result of the atomic vibrations of the constituent chromophores. The eigenstate fluctuations arise from disorder that is driven by vibrational dynamics with multiple characteristic timescales. The scalability of our ab initio excitonic computational framework across massively parallel architectures opens up the possibility of addressing a wide range of questions, including how specific dynamical motions impact both the pathways and efficiency of electronic energy-transfer within large supramolecular systems.

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Photosynthetic Light Harvesting

Cited by 4 publications

References 48 publications

Light Absorption and Energy Transfer in the Antenna Complexes of Photosynthetic Organisms

Light Absorption and Energy Transfer in the Antenna Complexes of Photosynthetic Organisms

Seagrass development in terrigenous‐influenced inner ramp settings during the middle Eocene (Urbasa–Andia Plateau, Western Pyrenees, North Spain)

Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model

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