scholarly journals Structural Diversity of Photosystem I and Its Light-Harvesting System in Eukaryotic Algae and Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Tianyu Bai ◽  
Lin Guo ◽  
Mingyu Xu ◽  
Lirong Tian
Keyword(s):  
Photosystem I ◽  
Light Harvesting ◽  
Structural Diversity ◽  
Spatial Arrangement ◽  
Oxygenic Photosynthesis ◽  
Light Harvesting Complexes ◽  
X Ray Crystallography ◽  
Photosynthetic Organisms ◽  
Eukaryotic Algae ◽  
Structural Details

Photosystem I (PSI) is one of the most efficient photoelectric apparatus in nature, converting solar energy into condensed chemical energy with almost 100% quantum efficiency. The ability of PSI to attain such high conversion efficiency depends on the precise spatial arrangement of its protein subunits and binding cofactors. The PSI structures of oxygenic photosynthetic organisms, namely cyanobacteria, eukaryotic algae, and plants, have undergone great variation during their evolution, especially in eukaryotic algae and vascular plants for which light-harvesting complexes (LHCI) developed that surround the PSI core complex. A detailed understanding of the functional and structural properties of this PSI-LHCI is not only an important foundation for understanding the evolution of photosynthetic organisms but is also useful for designing future artificial photochemical devices. Recently, the structures of such PSI-LHCI supercomplexes from red alga, green alga, diatoms, and plants were determined by X-ray crystallography and single-particle cryo-electron microscopy (cryo-EM). These findings provide new insights into the various structural adjustments of PSI, especially with respect to the diversity of peripheral antenna systems arising via evolutionary processes. Here, we review the structural details of the PSI tetramer in cyanobacteria and the PSI-LHCI and PSI-LHCI-LHCII supercomplexes from different algae and plants, and then discuss the diversity of PSI-LHCI in oxygenic photosynthesis organisms.

scholarly journals Photosynthetic light harvesting and thylakoid organization in a CRISPR/Cas9 Arabidopsis thaliana LHCB1 knockout mutant.

2021 ◽  
Author(s):  
Hamed Sattari Vayghan ◽  
Wojciech J Nawrocki ◽  
Christo Schiphorst ◽  
Dimitri Tolleter ◽  
Hu Chen ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Cross Section ◽  
Photosystem I ◽  
Absorption Cross Section ◽  
Light Harvesting ◽  
Higher Plants ◽  
Oxygenic Photosynthesis ◽  
Growth Delay ◽  
Absorption Cross ◽  
Light Harvesting Complexes

Light absorbed by chlorophylls of photosystem II and I drives oxygenic photosynthesis. Light-harvesting complexes increase the absorption cross-section of these photosystems. Furthermore, these complexes play a central role in photoprotection by dissipating the excess of absorbed light energy in an inducible and regulated fashion. In higher plants, the main light-harvesting complex is the trimeric LHCII. In this work, we used CRISPR/Cas9 to knockout the five genes encoding LHCB1, which is the major component of the trimeric LHCII. In absence of LHCB1 the accumulation of the other LHCII isoforms was only slightly increased, thereby resulting in chlorophyll loss leading to a pale green phenotype and growth delay. Photosystem II absorption cross-section was smaller while photosystem I absorption cross-section was unaffected. This altered the chlorophyll repartition between the two photosystems, favoring photosystem I excitation. The equilibrium of the photosynthetic electron transport was partially maintained by a lower photosystem I over photosystem II reaction center ratio and by the dephosphorylation of LHCII and photosystem II. Loss of LHCB1 altered the thylakoid structure, with less membrane layers per grana stack and reduced grana width. Stable LHCB1 knock out lines allow characterizing the role of this protein in light harvesting and acclimation and pave the way for future in vivo mutational analyses of LHCII.

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.

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 Functional analysis of Photosystem I light-harvesting complexes (Lhca) gene products of Chlamydomonas reinhardtii

2010 ◽  
Vol 1797 (2) ◽  
pp. 212-221 ◽  
Author(s):  
Milena Mozzo ◽  
Manuela Mantelli ◽  
Francesca Passarini ◽  
Stefano Caffarri ◽  
Roberta Croce ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Light Harvesting ◽  
Gene Products ◽  
Light Harvesting Complexes

scholarly journals Light’s interaction with pigments in chloroplasts: The murburn perspective, with special relevance to carotenoids

2020 ◽  
Author(s):  
Kelath Murali Manoj ◽  
Afsal Manekkathodi
Keyword(s):  
Light Harvesting ◽  
Reaction Centers ◽  
Oxygenic Photosynthesis ◽  
Physiological Data ◽  
Light Harvesting Complexes ◽  
Light Reaction ◽  
Historical Perspectives ◽  
Electron Emitters ◽  
Theoretical Foundations ◽  
Special Relevance

The prevailing understanding on photolytic photophosphorylation, the light reaction of oxygenic photosynthesis, considers the vast majority of the diverse pigments, chlorophyll binding proteins (CBPs) and light harvesting complexes (LHCs) as photon-energy relaying facets; only the two photosystems’ (PS) reaction centers’ chlorophyll a couplets are deemed to serve as photo-excitable electron emitters. Highlighting the historical perspectives involved, we present reasons why this conventional perception is unmet by theoretical foundations, unsupported by molecular awareness on the various pigments and unverified by physiological data available on chloroplasts. Further, we propose a simple diffusible reactive oxygen species (DROS)-based mechanism for correlating the functions of various light harvesting LHCs and CBPs with the reaction centers of PS I & II.

scholarly journals The Relationship between the Spatial Arrangement of Pigments and Exciton Transition Moments in Photosynthetic Light-Harvesting Complexes

2021 ◽  
Vol 22 (18) ◽  
pp. 10031
Author(s):  
Roman Y. Pishchalnikov ◽  
Denis D. Chesalin ◽  
Andrei P. Razjivin
Keyword(s):  
Light Harvesting ◽  
Purple Bacteria ◽  
Center Of Mass ◽  
Electron Transition ◽  
Spatial Arrangement ◽  
Excitation Energies ◽  
Light Harvesting Complexes ◽  
Exciton Transition ◽  
Transition Moments ◽  
The Relationship

Considering bacteriochlorophyll molecules embedded in the protein matrix of the light-harvesting complexes of purple bacteria (known as LH2 and LH1-RC) as examples of systems of interacting pigment molecules, we investigated the relationship between the spatial arrangement of the pigments and their exciton transition moments. Based on the recently reported crystal structures of LH2 and LH1-RC and the outcomes of previous theoretical studies, as well as adopting the Frenkel exciton Hamiltonian for two-level molecules, we performed visualizations of the LH2 and LH1 exciton transition moments. To make the electron transition moments in the exciton representation invariant with respect to the position of the system in space, a system of pigments must be translated to the center of mass before starting the calculations. As a result, the visualization of the transition moments for LH2 provided the following pattern: two strong transitions were outside of LH2 and the other two were perpendicular and at the center of LH2. The antenna of LH1-RC was characterized as having the same location of the strongest moments in the center of the complex, exactly as in the B850 ring, which actually coincides with the RC. Considering LH2 and LH1 as supermolecules, each of which has excitation energies and corresponding transition moments, we propose that the outer transitions of LH2 can be important for inter-complex energy exchange, while the inner transitions keep the energy in the complex; moreover, in the case of LH1, the inner transitions increased the rate of antenna-to-RC energy transfer.

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