scholarly journals Microscopic quantum coherence in a photosynthetic-light-harvesting antenna

2012 ◽  
Vol 370 (1972) ◽  
pp. 3672-3691 ◽  
Author(s):  
Jahan M. Dawlaty ◽  
Akihito Ishizaki ◽  
Arijit K. De ◽  
Graham R. Fleming
Keyword(s):  
Single Molecule ◽  
Quantum Coherence ◽  
Energy Transport ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Coherent Motion ◽  
Quantum Beats ◽  
Ensemble Averaging ◽  
Light Harvesting Antenna

We briefly review the coherent quantum beats observed in recent two-dimensional electronic spectroscopy experiments in a photosynthetic-light-harvesting antenna. We emphasize that the decay of the quantum beats in these experiments is limited by ensemble averaging. The in vivo dynamics of energy transport depends upon the local fluctuations of a single photosynthetic complex during the energy transfer time (a few picoseconds). Recent analyses suggest that it remains possible that the quantum-coherent motion may be robust under individual realizations of the environment-induced fluctuations contrary to intuition obtained from condensed phase spectroscopic measurements and reduced density matrices. This result indicates that the decay of the observed quantum coherence can be understood as ensemble dephasing. We propose a fluorescence-detected single-molecule experiment with phase-locked excitation pulses to investigate the coherent dynamics at the level of a single molecule without hindrance by ensemble averaging. We discuss the advantages and limitations of this method. We report our initial results on bulk fluorescence-detected coherent spectroscopy of the Fenna–Mathews–Olson complex.

scholarly journals Excitation energy transfer and equilibration process in LHCII studied by multidimensional electronic spectroscopy

2019 ◽  
Vol 205 ◽  
pp. 09038
Author(s):  
Thanh Nhut Do ◽  
Adriana Huerta-Viga ◽  
Cheng Zhang ◽  
Parveen Akhtar ◽  
Pawei J. Nowakowski ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Excitation Energy Transfer ◽  
Phenomenological Analysis ◽  
Two Dimensional ◽  
Light Harvesting Complex ◽  
Light Harvesting Complex Ii ◽  
Equilibration Process ◽  
Light Harvesting Antenna

Light-harvesting complex II (LHCII) – the light-harvesting antenna of Photosystem II – is a naturally abundant system that plays an important role in photosynthesis. In this study, we present a phenomenological analysis of the excitonic energy transfer in LHCII using ultrafast two-dimensional electronic spectroscopy, that we find compares well with previous theoretical and experimental results.

scholarly journals Evidence for coherent mixing of excited and charge-transfer states in the major plant light-harvesting antenna, LHCII

2017 ◽  
Vol 19 (34) ◽  
pp. 22877-22886 ◽  
Author(s):  
Charusheela Ramanan ◽  
Marco Ferretti ◽  
Henny van Roon ◽  
Vladimir I. Novoderezhkin ◽  
Rienk van Grondelle
Keyword(s):  
Fourier Transform ◽  
Charge Transfer ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Low Energy ◽  
Light Harvesting Antenna

2D electronic spectroscopy and Fourier transform maps suggest coherently coupled states at the low-energy edge of the LHCII excitonic manifold.

scholarly journals Watching cellular machinery in action, one molecule at a time

2016 ◽  
Vol 216 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Enrico Monachino ◽  
Lisanne M. Spenkelink ◽  
Antoine M. van Oijen
Keyword(s):  
Dynamic Behavior ◽  
Single Molecule ◽  
Protein Complexes ◽  
Imaging Techniques ◽  
Ensemble Averaging ◽  
Cellular Processes ◽  
Cellular Machinery

Single-molecule manipulation and imaging techniques have become important elements of the biologist’s toolkit to gain mechanistic insights into cellular processes. By removing ensemble averaging, single-molecule methods provide unique access to the dynamic behavior of biomolecules. Recently, the use of these approaches has expanded to the study of complex multiprotein systems and has enabled detailed characterization of the behavior of individual molecules inside living cells. In this review, we provide an overview of the various force- and fluorescence-based single-molecule methods with applications both in vitro and in vivo, highlighting these advances by describing their applications in studies on cytoskeletal motors and DNA replication. We also discuss how single-molecule approaches have increased our understanding of the dynamic behavior of complex multiprotein systems. These methods have shown that the behavior of multicomponent protein complexes is highly stochastic and less linear and deterministic than previously thought. Further development of single-molecule tools will help to elucidate the molecular dynamics of these complex systems both inside the cell and in solutions with purified components.

scholarly journals From isolated light-harvesting complexes to the thylakoid membrane: a single-molecule perspective

Nanophotonics ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 81-92 ◽  
Author(s):  
J. Michael Gruber ◽  
Pavel Malý ◽  
Tjaart P.J. Krüger ◽  
Rienk van Grondelle
Keyword(s):  
Single Molecule ◽  
Thylakoid Membrane ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Conformational Dynamics ◽  
Physical Models ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Fluorescence Measurements

AbstractThe conversion of solar radiation to chemical energy in plants and green algae takes place in the thylakoid membrane. This amphiphilic environment hosts a complex arrangement of light-harvesting pigment-protein complexes that absorb light and transfer the excitation energy to photochemically active reaction centers. This efficient light-harvesting capacity is moreover tightly regulated by a photoprotective mechanism called non-photochemical quenching to avoid the stress-induced destruction of the catalytic reaction center. In this review we provide an overview of single-molecule fluorescence measurements on plant light-harvesting complexes (LHCs) of varying sizes with the aim of bridging the gap between the smallest isolated complexes, which have been well-characterized, and the native photosystem. The smallest complexes contain only a small number (10–20) of interacting chlorophylls, while the native photosystem contains dozens of protein subunits and many hundreds of connected pigments. We discuss the functional significance of conformational dynamics, the lipid environment, and the structural arrangement of this fascinating nano-machinery. The described experimental results can be utilized to build mathematical-physical models in a bottom-up approach, which can then be tested on larger in vivo systems. The results also clearly showcase the general property of biological systems to utilize the same system properties for different purposes. In this case it is the regulated conformational flexibility that allows LHCs to switch between efficient light-harvesting and a photoprotective function.

scholarly journals Observation of dissipative chlorophyll-to-carotenoid energy transfer in light-harvesting complex II in membrane nanodiscs

2019 ◽  
Author(s):  
Minjung Son ◽  
Alberta Pinnola ◽  
Samuel C. Gordon ◽  
Roberto Bassi ◽  
Gabriela S. Schlau-Cohen
Keyword(s):  
Energy Transfer ◽  
Conformational Changes ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Local Environment ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii ◽  
Photosynthetic Antenna

<pre><p><a></a>Green plants prevent photodamage under high light conditions by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics of the chlorophyll and carotenoids to their surrounding protein. However, the mechanisms and site of dissipation are still debated, largely due to two challenges. First, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Second, experiments have been performed in detergent, which can induce non-native conformations, or <i>in vivo</i>, where contributions from the multiple complexes cannot be disentangled and are further obfuscated by laser-induced artifacts. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, light-harvesting complex II, in a near-native membrane. The membrane enhances two dissipative pathways, one of which was previously uncharacterized chlorophyll-to-carotenoid energy transfer. Our results highlight the sensitivity of the photophysics to the local environment, which may be used to control the balance between light harvesting and dissipation <i>in vivo</i>.</p></pre>

The architecture and function of the light-harvesting apparatus of purple bacteria: from single molecules to in vivo membranes

2006 ◽  
Vol 39 (3) ◽  
pp. 227-324 ◽  
Author(s):  
Richard J. Cogdell ◽  
Andrew Gall ◽  
Jürgen Köhler
Keyword(s):  
Quantum Mechanics ◽  
Energy Transfer ◽  
Single Molecule ◽  
Molecular Mechanisms ◽  
Light Harvesting ◽  
Structural Information ◽  
Purple Bacteria ◽  
Theoretical Background ◽  
Single Molecule Spectroscopy

1. Introduction 2292. Structures 2342.1 The structure of LH2 2342.2 Natural variants of peripheral antenna complexes 2422.3 RC–LH1 complexes 2423. Spectroscopy 2493.1 Steady-state spectroscopy 2493.2 Factors which affect the position of the Qy absorption band of Bchla 2494. Regulation of biosynthesis and assembly 2574.1 Regulation 2574.1.1 Oxygen 2574.1.2 Light 2584.1.2.1 AppA: blue-light-mediated regulation 2594.1.2.2 Bacteriophytochromes 2594.1.3 From the RC to the mature PSU 2614.2 Assembly 2614.2.1 LH1 2624.2.2 LH2 2635. Frenkel excitons 2655.1 General 2655.2 B800 2675.3 B850 2675.4 B850 delocalization 2736. Energy-transfer pathways: experimental results 2746.1 Theoretical background 2746.2 ‘Follow the excitation energy’ 2766.2.1 Bchla→Bchla energy transfer 2776.2.1.1 B800→B800 2776.2.1.2 B800→B850 2786.2.1.3 B850→B850 2796.2.1.4 B850→B875 2806.2.1.5 B875→RC 2806.2.2 Car[harr ]Bchla energy transfer 2817. Single-molecule spectroscopy 2847.1 Introduction to single-molecule spectroscopy 2847.2 Single-molecule spectroscopy on LH2 2857.2.1 Overview 2857.2.2 B800 2867.2.2.1 General 2867.2.2.2 Intra- and intercomplex disorder of site energies 2877.2.2.3 Electron-phonon coupling 2897.2.2.4 B800→B800 energy transfer revisited 2907.2.3 B850 2938. Quantum mechanics and the purple bacteria LH system 2989. Appendix 2999.1 A crash course on quantum mechanics 2999.2 Interacting dimers 30510. Acknowledgements 30611. References 307This review describes the structures of the two major integral membrane pigment complexes, the RC–LH1 ‘core’ and LH2 complexes, which together make up the light-harvesting system present in typical purple photosynthetic bacteria. The antenna complexes serve to absorb incident solar radiation and to transfer it to the reaction centres, where it is used to ‘power’ the photosynthetic redox reaction and ultimately leads to the synthesis of ATP. Our current understanding of the biosynthesis and assembly of the LH and RC complexes is described, with special emphasis on the roles of the newly described bacteriophytochromes. Using both the structural information and that obtained from a wide variety of biophysical techniques, the details of each of the different energy-transfer reactions that occur, between the absorption of a photon and the charge separation in the RC, are described. Special emphasis is given to show how the use of single-molecule spectroscopy has provided a more detailed understanding of the molecular mechanisms involved in the energy-transfer processes. We have tried, with the help of an Appendix, to make the details of the quantum mechanics that are required to appreciate these molecular mechanisms, accessible to mathematically illiterate biologists. The elegance of the purple bacterial light-harvesting system lies in the way in which it has cleverly exploited quantum mechanics.

Changes in in vivo fluorescence quenching in rye and barley as a function of reduced PSII light harvesting antenna size

1994 ◽  
Vol 91 (4) ◽  
pp. 551-558 ◽  
Author(s):  
Stefan Falk ◽  
Marianna Krol ◽  
Denis P. Maxwell ◽  
David A. Rezansoff ◽  
Gordon R. Gray ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Light Harvesting ◽  
Antenna Size ◽  
In Vivo Fluorescence ◽  
Light Harvesting Antenna

scholarly journals Live-cell imaging of photosystem II antenna dissociation during state transitions

2009 ◽  
Vol 107 (5) ◽  
pp. 2337-2342 ◽  
Author(s):  
Masakazu Iwai ◽  
Makio Yokono ◽  
Noriko Inada ◽  
Jun Minagawa
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Light Harvesting ◽  
Live Cells ◽  
State Transitions ◽  
Fluorescence Lifetime Imaging ◽  
Energy Redistribution ◽  
Dominant Component ◽  
Light Harvesting Antenna

Plants and green algae maintain efficient photosynthesis under changing light environments by adjusting their light-harvesting capacity. It has been suggested that energy redistribution is brought about by shuttling the light-harvesting antenna complex II (LHCII) between photosystem II (PSII) and photosystem I (PSI) (state transitions), but such molecular remodeling has never been demonstrated in vivo. Here, using chlorophyll fluorescence lifetime imaging microscopy, we visualized phospho-LHCII dissociation from PSII in live cells of the green alga Chlamydomonas reinhardtii. Induction of energy redistribution in wild-type cells led to an increase in, and spreading of, a 250-ps lifetime chlorophyll fluorescence component, which was not observed in the stt7 mutant incapable of state transitions. The 250-ps component was also the dominant component in a mutant containing the light-harvesting antenna complexes but no photosystems. The appearance of the 250-ps component was accompanied by activation of LHCII phosphorylation, supporting the visualization of phospho-LHCII dissociation. Possible implications of the unbound phospho-LHCII on energy dissipation are discussed.

Changes in in vivo fluorescence quenching in rye and barley as a function of reduced PSII light harvesting antenna size

1994 ◽  
Vol 91 (4) ◽  
pp. 551-558 ◽  
Author(s):  
Stefan Falk ◽  
Marianna Krol ◽  
Denis P. Maxwell ◽  
David A. Rezansoff ◽  
Gordon R. Gray ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Light Harvesting ◽  
Antenna Size ◽  
In Vivo Fluorescence ◽  
Light Harvesting Antenna
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