scholarly journals Recycling of energy dissipated as heat accounts for high activity of Photosystem II

2019 ◽  
Author(s):  
Monika Zubik ◽  
Rafal Luchowski ◽  
Dariusz Kluczyk ◽  
Wojciech Grudzinski ◽  
Magdalena Maksim ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Energy Levels ◽  
Photosynthetic Apparatus ◽  
Low Energy ◽  
Reaction Centre ◽  
Thermally Driven ◽  
Spontaneous Relaxation ◽  
Energy Dissipated ◽  
Life On Earth ◽  
Pigment Protein Complex

ABSTRACTPhotosystem II (PSII) converts light into chemical energy powering almost entire life on Earth. The primary photovoltaic reaction in the PSII reaction centre requires energy corresponding to 680 nm that is significantly higher than in the case of the low-energy states in the antenna complexes involved in the harvesting of excitations driving PSII. Here we show that despite seemingly insufficient energy, the low-energy excited states can power PSII thanks to the activity of the thermally-driven up-conversion. We demonstrate the operation of this mechanism both in intact leaves and in isolated pigment-protein complex LHCII. A mechanism is proposed, according to which the effective utilization of thermal energy in the photosynthetic apparatus is possible owing to the formation of LHCII supramolecular structures, leading to the coupled energy levels, corresponding to approx. 680 nm and 700 nm, capable of exchanging excitation energy through the spontaneous relaxation and the thermal up-conversion.TOC GRAPHICS

scholarly journals Structural basis for the absence of low-energy chlorophylls responsible for photoprotection from a primitive cyanobacterial PSI

2021 ◽  
Author(s):  
Koji Kato ◽  
Tasuku Hamaguchi ◽  
Ryo Nagao ◽  
Keisuke Kawakami ◽  
Yoshifumi Ueno ◽  
...  
Keyword(s):  
Co2 Fixation ◽  
Energy Levels ◽  
Low Energy ◽  
Structural Basis ◽  
Photosynthetic Organisms ◽  
Cryo Electron Microscopy ◽  
Evolutionary Changes ◽  
Eukaryotic Organisms ◽  
Pigment Protein Complex ◽  
Resolution Structure

Photosystem I (PSI) of photosynthetic organisms is a multi-subunit pigment-protein complex and functions in light harvesting and photochemical charge-separation reactions, followed by reduction of NADP to NADPH required for CO2 fixation. PSI from different photosynthetic organisms has a variety of chlorophylls (Chls), some of which are at lower-energy levels than its reaction center P700, a special pair of Chls, and are called low-energy Chls. However, the site of low-energy Chls is still under debate. Here, we solved a 2.04-Å resolution structure of a PSI trimer by cryo-electron microscopy from a primitive cyanobacterium Gloeobacter violaceus PCC 7421, which has no low-energy Chls. The structure showed absence of some subunits commonly found in other cyanobacteria, confirming the primitive nature of this cyanobacterium. Comparison with the known structures of PSI from other cyanobacteria and eukaryotic organisms reveals that one dimeric and one trimeric Chls are lacking in the Gloeobacter PSI. The dimeric and trimeric Chls are named Low1 and Low2, respectively. Low2 does not exist in some cyanobacterial and eukaryotic PSIs, whereas Low1 is absent only in Gloeobacter. Since Gloeobacter is susceptible to light, this indicates that Low1 serves as a main photoprotection site in most oxyphototrophs, whereas Low2 is involved in either energy transfer or energy quenching in some of the oxyphototrophs. Thus, these findings provide insights into not only the functional significance of low-energy Chls in PSI, but also the evolutionary changes of low-energy Chls responsible for the photoprotection machinery from photosynthetic prokaryotes to eukaryotes.

Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

1986 ◽  
Vol 41 (5-6) ◽  
pp. 597-603 ◽  
Author(s):  
Aloysius Wild ◽  
Matthias Höpfner ◽  
Wolfgang Rühle ◽  
Michael Richter
Keyword(s):  
Photosystem Ii ◽  
Functional Organization ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Molar Ratio ◽  
Light Conditions ◽  
Low Light ◽  
Pigment System ◽  
Transport Chain ◽  
The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

A fifth chloroplast-encoded polypeptide is present in the photosystem II reaction centre complex

FEBS Letters ◽  
1989 ◽  
Vol 242 (2) ◽  
pp. 259-262 ◽  
Author(s):  
A.N. Webber ◽  
L. Packman ◽  
D.J. Chapman ◽  
J. Barber ◽  
J.C. Gray
Keyword(s):  
Photosystem Ii ◽  
Reaction Centre

Low-energy levels and gamma transitions inCo58

1975 ◽  
Vol 11 (3) ◽  
pp. 1042-1047 ◽  
Author(s):  
B. J. Brunner ◽  
R. G. Arns ◽  
S. E. Caldwell ◽  
C. M. Rozsa ◽  
J. W. Smith ◽  
...  
Keyword(s):  
Energy Levels ◽  
Low Energy ◽  
Gamma Transitions

scholarly journals On the performance of a photosystem II reaction centre-based photocell

2017 ◽  
Vol 8 (10) ◽  
pp. 6871-6880 ◽  
Author(s):  
Richard Stones ◽  
Hoda Hossein-Nejad ◽  
Rienk van Grondelle ◽  
Alexandra Olaya-Castro
Keyword(s):  
Photosystem Ii ◽  
Current Noise ◽  
Reaction Centre ◽  
Electron Counting ◽  
The Mean ◽  
Counting Statistics ◽  
Mean Current

We investigate the performance of a theoretical photosystem II reaction centre-inspired photocell device through the framework of electron counting statistics. In particular we look at the effect of a structured vibrational environment on the mean current and current noise.

scholarly journals Low-energy levels calculation for 193Ir

2006 ◽  
Vol 36 (4b) ◽  
pp. 1354-1356
Author(s):  
Guilherme Soares Zahn ◽  
Cibele Bugno Zamboni ◽  
Frederico Antonio Genezini ◽  
Joel Mesa-Hormaza ◽  
Manoel Tiago Freitas da Cruz
Keyword(s):  
Energy Levels ◽  
Low Energy

scholarly journals Impact of saline solution on growth and photosystem II during in vitro cultivation of Bromelia antiacantha (Bromeliaceae)

Rodriguésia ◽  
2021 ◽  
Vol 72 ◽  
Author(s):  
Rosiane Cipriano ◽  
João Paulo Rodrigues Martins ◽  
Luiz Carlos de Almeida Rodrigues ◽  
Antelmo Ralph Falqueto ◽  
Andreia Barcelos Passos Lima Gontijo
Keyword(s):  
Photosystem Ii ◽  
Saline Solution ◽  
Growth Traits ◽  
Photosynthetic Apparatus ◽  
Solution Culture ◽  
In Vitro Cultivation ◽  
Ms Medium ◽  
Number Of Leaves ◽  
Positive Effect

Abstract In vitro cultivation is a technique with wide application for micropropagation. However, each species has specific mineral needs for this type of cultivation. The objective was to assess the impacts of the saline solution culture medium on the performance of the photosynthetic apparatus and growth of Bromelia antiacantha during in vitro cultivation, and thus to elucidate the mitigation of the nutritional imbalance that can interfere in the electron transport in the plants. Plants were cultivated in a salt concentration gradient of MS medium (0%, 25%, 50%, 75% or 100%). The growth traits and fluorescence a chlorophyll were analyzed. Intermediate concentrations of MS medium resulted in plants with a larger number of leaves and longer root length. The OJIP curves and results of the JIP test showed that the plants grown without MS salts presented less efficient photosystem II (PSII), as indicated by the performance index [Pi(total)]. In contrast, the intermediate concentrations (MS 25% and 50%) had a positive effect on the performance of the photosynthetic apparatus. The MS 25% medium can be used for in vitro cultivation of B. antiacantha, enabling the development of plants with suitable physiological qualities for planting in the field.

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