scholarly journals Metal-Enhanced Fluorescence of Chlorophylls in Single Light-Harvesting Complexes

2009 ◽  
Vol 1208 ◽  
Author(s):  
Sebastian Mackowski ◽  
Dawid Piatkowski ◽  
Stephan Wörmke ◽  
Achim Hartschuh ◽  
Christoph Bräeuchle ◽  
...  
Keyword(s):  
Single Molecule ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Fold Increase ◽  
Metal Nanoparticle ◽  
Metal Nanostructures ◽  
Enhanced Fluorescence ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex

AbstractWe show that the fluorescence of peridinin-chlorophyll a-protein complexes can be strongly enhanced via coupling with plasmon excitations localized in metal nanostructures. The results of ensemble and single-molecule spectroscopy experiments at room temperature demonstrate six-fold increase of the emission intensity of the light-harvesting complex when it is placed in the vicinity of chemically prepared silver islands. Irrespective of the enhancement, we observe no effect of the metal nanoparticle on the fluorescence emission energy of the complex. This observation implies that plasmon excitations may be applied for controlling the optical properties of complex biomolecules.

scholarly journals Metal-Enhanced Fluorescence of Chlorophylls in Light-Harvesting Complexes Coupled to Silver Nanowires

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Dorota Kowalska ◽  
Bartosz Krajnik ◽  
Maria Olejnik ◽  
Magdalena Twardowska ◽  
Nikodem Czechowski ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Protein Complexes ◽  
Silver Nanowires ◽  
Reference Sample ◽  
Fluorescence Emission ◽  
Enhanced Fluorescence ◽  
Metal Enhanced Fluorescence ◽  
Light Harvesting Complexes ◽  
Time Resolved ◽  
Chlorophyll Protein

We investigate metal-enhanced fluorescence of peridinin-chlorophyll protein coupled to silver nanowires using optical microscopy combined with spectrally and time-resolved fluorescence techniques. In particular we study two different sample geometries: first, in which the light-harvesting complexes are deposited onto silver nanowires, and second, where solution of both nanostructures are mixed prior deposition on a substrate. The results indicate that for the peridinin-chlorophyll complexes placed in the vicinity of the silver nanowires we observe higher intensities of fluorescence emission as compared to the reference sample, where no nanowires are present. Enhancement factors estimated for the sample where the light-harvesting complexes are mixed together with the silver nanowires prior deposition on a substrate are generally larger in comparison to the other geometry of a hybrid nanostructure. While fluorescence spectra are identical both in terms of overall shape and maximum wavelength for peridinin-chlorophyll-protein complexes both isolated and coupled to metallic nanostructures, we conclude that interaction with plasmon excitations in the latter remains neutral to the functionality of the biological system. Fluorescence transients measured for the PCP complexes coupled to the silver nanowires indicate shortening of the fluorescence lifetime pointing towards modifications of radiative rate due to plasmonic interactions. Our results can be applied for developing ways to plasmonically control the light-harvesting capability of photosynthetic complexes.

scholarly journals Structure of the stress-related LHCSR1 complex determined by an integrated computational strategy

2021 ◽  
Author(s):  
Ingrid Guarnetti Prandi ◽  
Vladislav Sláma ◽  
Cristina Pecorilla ◽  
Lorenzo Cupellini ◽  
Benedetta Mennucci
Keyword(s):  
Structural Model ◽  
Light Harvesting ◽  
Structural Information ◽  
Protein Complexes ◽  
Complex Stress ◽  
Main Function ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Pigment Protein Complexes ◽  
Computational Strategy

Light-harvesting complexes (LHCs) are pigment-protein complexes whose main function is to capture sunlight and transfer the energy to reaction centers of photosystems. In response to varying light conditions, LH complexes also play photoregulation and photoprotection roles. In algae and mosses, a sub-family of LHCs, Light-Harvesting complex stress related (LHCSR), is responsible for photoprotective quenching. Despite their functional and evolutionary importance, no direct structural information on LHCSRs is available that can explain their unique properties. In this work we propose a structural model of LHCSR1 from the moss P. Patens, obtained through an integrated computational strategy that combines homology modeling, molecular dynamics, and multiscale quantum chemical calculations. The model is validated by reproducing the spectral properties of LHCSR1. Our model reveals the structural specificity of LHCSR1, as compared with the CP29 LH complex, and poses the basis for understanding photoprotective quenching in mosses.

scholarly journals The light-harvesting complexes of higher-plant Photosystem I: Lhca1/4 and Lhca2/3 form two red-emitting heterodimers

2011 ◽  
Vol 433 (3) ◽  
pp. 477-485 ◽  
Author(s):  
Emilie Wientjes ◽  
Roberta Croce
Keyword(s):  
Photosystem I ◽  
Light Harvesting ◽  
Fluorescence Emission ◽  
Light Response ◽  
Native State ◽  
Higher Plant ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Wavelength Emission

The outer antenna of higher-plant PSI (Photosystem I) is composed of four complexes [Lhc (light-harvesting complex) a1–Lhca4] belonging to the light-harvesting protein family. Difficulties in their purification have so far prevented the determination of their properties and most of the knowledge about Lhcas has been obtained from the study of the in vitro reconstituted antennas. In the present study we were able to purify the native complexes, showing that Lhca2/3 and Lhca1/4 form two functional heterodimers. Both dimers show red-fluorescence emission with maxima around 730 nm, as in the intact PSI complex. This indicates that the dimers are in their native state and that LHCI-680, which was previously assumed to be part of the PSI antenna, does not represent the native state of the system. The data show that the light-harvesting properties of the two dimers are functionally identical, concerning absorption, long-wavelength emission and fluorescence quantum yield, whereas they differ in their high-light response. Implications of the present study for the understanding of the energy transfer process in PSI are discussed. Finally, the comparison of the properties of the native dimers with those of the reconstituted complexes demonstrates that all of the major properties of the Lhcas are reproduced in the in vitro systems.

scholarly journals A photosynthetic antenna complex foregoes unity carotenoid-to-bacteriochlorophyll energy transfer efficiency to ensure photoprotection

2020 ◽  
Vol 117 (12) ◽  
pp. 6502-6508 ◽  
Author(s):  
Dariusz M. Niedzwiedzki ◽  
David J. K. Swainsbury ◽  
Daniel P. Canniffe ◽  
C. Neil Hunter ◽  
Andrew Hitchcock
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Light Harvesting Complexes ◽  
Antenna Complex ◽  
Pigment Protein Complexes

Carotenoids play a number of important roles in photosynthesis, primarily providing light-harvesting and photoprotective energy dissipation functions within pigment–protein complexes. The carbon–carbon double bond (C=C) conjugation length of carotenoids (N), generally between 9 and 15, determines the carotenoid-to-(bacterio)chlorophyll [(B)Chl] energy transfer efficiency. Here we purified and spectroscopically characterized light-harvesting complex 2 (LH2) fromRhodobacter sphaeroidescontaining theN= 7 carotenoid zeta (ζ)-carotene, not previously incorporated within a natural antenna complex. Transient absorption and time-resolved fluorescence show that, relative to the lifetime of the S1state of ζ-carotene in solvent, the lifetime decreases ∼250-fold when ζ-carotene is incorporated within LH2, due to transfer of excitation energy to the B800 and B850 BChlsa. These measurements show that energy transfer proceeds with an efficiency of ∼100%, primarily via the S1→ Qxroute because the S1→ S0fluorescence emission of ζ-carotene overlaps almost perfectly with the Qxabsorption band of the BChls. However, transient absorption measurements performed on microsecond timescales reveal that, unlike the nativeN≥ 9 carotenoids normally utilized in light-harvesting complexes, ζ-carotene does not quench excited triplet states of BChla, likely due to elevation of the ζ-carotene triplet energy state above that of BChla. These findings provide insights into the coevolution of photosynthetic pigments and pigment–protein complexes. We propose that theN≥ 9 carotenoids found in light-harvesting antenna complexes represent a vital compromise that retains an acceptable level of energy transfer from carotenoids to (B)Chls while allowing acquisition of a new, essential function, namely, photoprotective quenching of harmful (B)Chl triplets.

Isolation and characterization of three membranebound chlorophyll-protein complexes from four dinoflagellate species

1993 ◽  
Vol 340 (1294) ◽  
pp. 381-392 ◽  
Keyword(s):  
Energy Transfer ◽  
Photosystem I ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Gradient Centrifugation ◽  
Water Soluble ◽  
Molar Ratio ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Isolation And Characterization

Employing discontinuous sucrose density gradient centrifugation of n -dodecyl β-d-maltoside-solubilized thylakoid membranes, three chlorophyll (Chl)-protein complexes containing Chl a , Chl c 2 and peridinin in different proportions, were isolated from the dinoflagellates Symbiodinium microadriaticum, S. kawagutii, S. pilosum and Heterocapsa pygmaea . In S. microadriaticum , the first complex, containing 13% of the total cellular Chl a , and minor quantities of Chl c 2 and peridinin, is associated with polypeptides with apparent molecular mass ( M r ) of 8-9 kDa, and demonstrated inefficient energy transfer from the accessory pigments to Chl a . The second complex contains Chl a , Chl c 2 and peridinin in a molar ratio of 1:1:2, associated with two apoproteins of M r 19-20 kDa, and comprises 45%, 75% and 70%, respectively, of the cellular Chl a , Chl c 2 and peridinin. The efficient energy transfer from Chl c 2 and peridinin to Chl a in this complex is supportive of a light-harvesting function. This Chl a - c 2 - peridin-protein complex represents the major light-harvesting complex in dinoflagellates. The third complex obtained contains 12% of the cellular Chl a , and appears to be the core of photosystem I, associated with a light-harvesting complex. This complex is spectroscopically similar to analogous preparations from different taxonomic groups, but demonstrates a unique apoprotein composition. Antibodies against the water-soluble peridinin-Chl a -protein (sPCP) light-harvesting complexes failed to cross-react with any of the thylakoid-associated complexes, as did antibodies against Chl a - c -fucoxanthin apoprotein (from diatoms). Antibodies against the P 700 apoprotein of plants did not cross-react with the photosystem I complex. Similar results were observed in the other dinoflagellates.

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 Strong plasmonic fluorescence enhancement of individual plant light-harvesting complexes

Nanoscale ◽  
2019 ◽  
Vol 11 (32) ◽  
pp. 15139-15146 ◽  
Author(s):  
Farooq Kyeyune ◽  
Joshua L. Botha ◽  
Bertus van Heerden ◽  
Pavel Malý ◽  
Rienk van Grondelle ◽  
...  
Keyword(s):  
Fluorescence Enhancement ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Photosynthetic Pigment ◽  
Individual Plant ◽  
Enhanced Fluorescence ◽  
Light Harvesting Complexes ◽  
Plasmon Enhanced Fluorescence ◽  
Pigment Protein Complexes

Plasmon-enhanced fluorescence for detection of weakly emitting individual photosynthetic pigment-protein complexes.

scholarly journals How reduced excitonic coupling enhances light harvesting in the main photosynthetic antennae of diatoms

2017 ◽  
Vol 114 (52) ◽  
pp. E11063-E11071 ◽  
Author(s):  
Tjaart P. J. Krüger ◽  
Pavel Malý ◽  
Maxime T. A. Alexandre ◽  
Tomáš Mančal ◽  
Claudia Büchel ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Single Molecule ◽  
Light Harvesting ◽  
Excitation Energy Transfer ◽  
Direct Result ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Enhanced Sensitivity ◽  
Excitonic Interactions ◽  
Excitonic Coupling

Strong excitonic interactions are a key design strategy in photosynthetic light harvesting, expanding the spectral cross-section for light absorption and creating considerably faster and more robust excitation energy transfer. These molecular excitons are a direct result of exceptionally densely packed pigments in photosynthetic proteins. The main light-harvesting complexes of diatoms, known as fucoxanthin–chlorophyll proteins (FCPs), are an exception, displaying surprisingly weak excitonic coupling between their chlorophyll (Chl) a’s, despite a high pigment density. Here, we show, using single-molecule spectroscopy, that the FCP complexes of Cyclotella meneghiniana switch frequently into stable, strongly emissive states shifted 4–10 nm toward the red. A few percent of isolated FCPa complexes and ∼20% of isolated FCPb complexes, on average, were observed to populate these previously unobserved states, percentages that agree with the steady-state fluorescence spectra of FCP ensembles. Thus, the complexes use their enhanced sensitivity to static disorder to increase their light-harvesting capability in a number of ways. A disordered exciton model based on the structure of the main plant light-harvesting complex explains the red-shifted emission by strong localization of the excitation energy on a single Chl a pigment in the terminal emitter domain due to very specific pigment orientations. We suggest that the specific construction of FCP gives the complex a unique strategy to ensure that its light-harvesting function remains robust in the fluctuating protein environment despite limited excitonic interactions.

Enhanced-Fluorescence of a Dye on DNA- assembled Gold Nano-Dimers Discriminated by Lifetime Correlation Spectroscopy

2017 ◽  
Author(s):  
Pedro M. R. Paulo ◽  
David Botequim ◽  
Agnieszka Jóskowiak ◽  
Sofia Martins ◽  
Duarte M. F. Prazeres ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescence Emission ◽  
Directed Assembly ◽  
Plasmon Mode ◽  
Correlation Spectroscopy ◽  
Enhanced Fluorescence ◽  
Detection Volume ◽  
Relaxation Component ◽  
Good Agreement ◽  
Confocal Detection

<div> <div> <div> <p>We have employed DNA-directed assembly to prepare dimers of gold nanoparticles and used their longitudinally coupled plasmon mode to enhance the fluorescence emission of an organic red-emitting dye, Atto-655. The plasmon- enhanced fluorescence of this dye using dimers of 80 nm particles was measured at single molecule detection level. The top enhancement factors were above 1000-fold in 71% of the dimers within a total of 32 dimers measured, and, in some cases, they reached almost 4000-fold, in good agreement with model simulations. Additionally, fluorescence lifetime correlation analysis enabled the separation of enhanced from non-enhanced emission simultaneously collected in our confocal detection volume. This approach allowed us to recover a short relaxation component exclusive to enhanced emission that is attributed to the interaction of the dye with DNA in the interparticle gaps. </p> </div> </div> </div>

scholarly journals Fast Diffusion of the Unassembled PetC1-GFP Protein in the Cyanobacterial Thylakoid Membrane

Life ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Radek Kaňa ◽  
Gábor Steinbach ◽  
Roman Sobotka ◽  
György Vámosi ◽  
Josef Komenda
Keyword(s):  
Membrane Proteins ◽  
Single Molecule ◽  
Protein Interactions ◽  
Thylakoid Membrane ◽  
Protein Complexes ◽  
Correlation Spectroscopy ◽  
Membrane Microdomains ◽  
Fast Diffusion ◽  
Light Harvesting Complexes ◽  
Term Survival

Biological membranes were originally described as a fluid mosaic with uniform distribution of proteins and lipids. Later, heterogeneous membrane areas were found in many membrane systems including cyanobacterial thylakoids. In fact, cyanobacterial pigment–protein complexes (photosystems, phycobilisomes) form a heterogeneous mosaic of thylakoid membrane microdomains (MDs) restricting protein mobility. The trafficking of membrane proteins is one of the key factors for long-term survival under stress conditions, for instance during exposure to photoinhibitory light conditions. However, the mobility of unbound ‘free’ proteins in thylakoid membrane is poorly characterized. In this work, we assessed the maximal diffusional ability of a small, unbound thylakoid membrane protein by semi-single molecule FCS (fluorescence correlation spectroscopy) method in the cyanobacterium Synechocystis sp. PCC6803. We utilized a GFP-tagged variant of the cytochrome b6f subunit PetC1 (PetC1-GFP), which was not assembled in the b6f complex due to the presence of the tag. Subsequent FCS measurements have identified a very fast diffusion of the PetC1-GFP protein in the thylakoid membrane (D = 0.14 − 2.95 µm2s−1). This means that the mobility of PetC1-GFP was comparable with that of free lipids and was 50–500 times higher in comparison to the mobility of proteins (e.g., IsiA, LHCII—light-harvesting complexes of PSII) naturally associated with larger thylakoid membrane complexes like photosystems. Our results thus demonstrate the ability of free thylakoid-membrane proteins to move very fast, revealing the crucial role of protein–protein interactions in the mobility restrictions for large thylakoid protein complexes.

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