Size variability of the unit building block of peripheral light-harvesting antennas as a strategy for effective functioning of antennas of variable size that is controlled in vivo by light intensity

Abstract In response to changing light quantity and quality, photosynthetic organisms perform state transitions, a process which optimizes photosynthetic yield and mitigates photo-damage. The serine/threonine-protein kinase STN7 phosphorylates the light-harvesting complex of photosystem II (PSII; light-harvesting complex II), which then migrates from PSII to photosystem I (PSI), thereby rebalancing the light excitation energy between the photosystems and restoring the redox poise of the photosynthetic electron transport chain. Two conserved cysteines forming intra- or intermolecular disulfide bonds in the lumenal domain (LD) of STN7 are essential for the kinase activity although it is still unknown how activation of the kinase is regulated. In this study, we show lumen thiol oxidoreductase 1 (LTO1) is co-expressed with STN7 in Arabidopsis (Arabidopsis thaliana) and interacts with the LD of STN7 in vitro and in vivo. LTO1 contains thioredoxin (TRX)-like and vitamin K epoxide reductase domains which are related to the disulfide-bond formation system in bacteria. We further show that the TRX-like domain of LTO1 is able to oxidize the conserved lumenal cysteines of STN7 in vitro. In addition, loss of LTO1 affects the kinase activity of STN7 in Arabidopsis. Based on these results, we propose that LTO1 helps to maintain STN7 in an oxidized active state in state 2 through redox interactions between the lumenal cysteines of STN7 and LTO1.

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Optical Bloch equations for light harvesting complexes: pump probe spectra and saturation dynamics at high light intensity excitation

CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference ◽

10.1109/cleoe-eqec.2009.5192700 ◽

2009 ◽

Author(s):

Marten Richter ◽

Alexander Carmele ◽

Thomas Renger ◽

Andreas Knorr

Keyword(s):

Light Intensity ◽

Light Harvesting ◽

High Light Intensity ◽

High Light ◽

Bloch Equations ◽

Optical Bloch Equations ◽

Light Harvesting Complexes ◽

Pump Probe

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Optical Measurement of Blood Oxygen Saturation of Dental Pulp

ISRN Biomedical Engineering ◽

10.1155/2013/502869 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 5

Author(s):

Satoko Kakino ◽

Shinya Kushibiki ◽

Azusa Yamada ◽

Zenzo Miwa ◽

Yuzo Takagi ◽

...

Keyword(s):

Light Intensity ◽

Oxygen Saturation ◽

Dental Pulp ◽

Optical Measurement ◽

Blood Oxygen ◽

Arterial Pulse ◽

Blood Oxygen Saturation ◽

Visible Wavelengths

The applicability of arterial pulse oximetry to dental pulp was demonstrated using in vitro and in vivo measurements. First, porcine blood of known oxygen saturation (SO2) was circulated through extracted human upper incisors, while transmitted-light plethysmography was performed using three different visible wavelengths. From the light intensity waveforms measured in vitro, a parameter that is statistically correlated to SO2 was calculated using the pulsatile/nonpulsatile component ratios of two wavelengths for different SO2. Then, values were measured in vivo for living incisors, and the corresponding SO2 values were calculated using the results of in vitro measurements. The estimated SO2 values of the upper central incisors measured in vivo were from 71.0 to 92.7%. This study showed the potential to measure the oxygen saturation changes to identify the sign of pulpal inflammation.

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Building-block synthesis of porphyrin light-harvesting arrays

Journal of the American Chemical Society ◽

10.1021/ja00069a068 ◽

1993 ◽

Vol 115 (16) ◽

pp. 7519-7520 ◽

Cited By ~ 152

Author(s):

Sreedharan Prathapan ◽

Thomas E. Johnson ◽

Jonathan S. Lindsey

Keyword(s):

Building Block ◽

Light Harvesting

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Microscopic quantum coherence in a photosynthetic-light-harvesting antenna

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0207 ◽

2012 ◽

Vol 370 (1972) ◽

pp. 3672-3691 ◽

Cited By ~ 28

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.

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Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

10.1101/2020.07.10.197483 ◽

2020 ◽

Author(s):

Julianne M. Troiano ◽

Federico Perozeni ◽

Raymundo Moya ◽

Luca Zuliani ◽

Kwangryul Baek ◽

...

Keyword(s):

Chlamydomonas Reinhardtii ◽

Light Harvesting ◽

Complex Stress ◽

Excess Energy ◽

Photochemical Quenching ◽

Light Harvesting Complexes ◽

Light Harvesting Complex ◽

Non Photochemical Quenching

AbstractUnder high light conditions, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating excess absorbed energy, which is called non-photochemical quenching (NPQ). In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via pH and serves as a quenching site. However, the mechanisms by which LHCSR3 functions have not been determined. Using a combined in vivo and in vitro approach, we identify two parallel yet distinct quenching processes, individually controlled by pH and carotenoid composition, and their likely molecular origin within LHCSR3 from Chlamydomonas reinhardtii. The pH-controlled quenching is removed within a mutant LHCSR3 that lacks the protonable residues responsible for sensing pH. Constitutive quenching in zeaxanthin-enriched systems demonstrates zeaxanthin-controlled quenching, which may be shared with other light-harvesting complexes. We show that both quenching processes prevent the formation of damaging reactive oxygen species, and thus provide distinct timescales and mechanisms of protection in a changing environment.

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