scholarly journals Unique organization of photosystem I–light-harvesting supercomplex revealed by cryo-EM from a red alga

2018 ◽  
Vol 115 (17) ◽  
pp. 4423-4428 ◽  
Author(s):  
Xiong Pi ◽  
Lirong Tian ◽  
Huai-En Dai ◽  
Xiaochun Qin ◽  
Lingpeng Cheng ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Photosystem I ◽  
Light Harvesting ◽  
Higher Plants ◽  
Red Alga ◽  
Cyanidioschyzon Merolae ◽  
Higher Plant ◽  
Light Harvesting Complex ◽  
Red Algal ◽  
Eukaryotic Organisms

Photosystem I (PSI) is one of the two photosystems present in oxygenic photosynthetic organisms and functions to harvest and convert light energy into chemical energy in photosynthesis. In eukaryotic algae and higher plants, PSI consists of a core surrounded by variable species and numbers of light-harvesting complex (LHC)I proteins, forming a PSI-LHCI supercomplex. Here, we report cryo-EM structures of PSI-LHCR from the red alga Cyanidioschyzon merolae in two forms, one with three Lhcr subunits attached to the side, similar to that of higher plants, and the other with two additional Lhcr subunits attached to the opposite side, indicating an ancient form of PSI-LHCI. Furthermore, the red algal PSI core showed features of both cyanobacterial and higher plant PSI, suggesting an intermediate type during evolution from prokaryotes to eukaryotes. The structure of PsaO, existing in eukaryotic organisms, was identified in the PSI core and binds three chlorophylls a and may be important in harvesting energy and in mediating energy transfer from LHCII to the PSI core under state-2 conditions. Individual attaching sites of LHCRs with the core subunits were identified, and each Lhcr was found to contain 11 to 13 chlorophylls a and 5 zeaxanthins, which are apparently different from those of LHCs in plant PSI-LHCI. Together, our results reveal unique energy transfer pathways different from those of higher plant PSI-LHCI, its adaptation to the changing environment, and the possible changes of PSI-LHCI during evolution from prokaryotes to eukaryotes.

Regulation of photosystem I-light-harvesting complex I from a red alga Cyanidioschyzon merolae in response to light intensities

2020 ◽  
Vol 146 (1-3) ◽  
pp. 287-297
Author(s):  
Lijing Chang ◽  
Lirong Tian ◽  
Fei Ma ◽  
Zhiyuan Mao ◽  
Xiaochi Liu ◽  
...  
Keyword(s):  
Photosystem I ◽  
Complex I ◽  
Light Harvesting ◽  
Red Alga ◽  
Cyanidioschyzon Merolae ◽  
Light Harvesting Complex ◽  
Light Intensities

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.

The structure of the Physcomitrium Patens Photosystem I Reveals a Unique Lhca2 Paralogue replacing Lhca4

2021 ◽  
Author(s):  
Yuval Mazor ◽  
Christopher Gorski ◽  
Reece Riddle ◽  
Hila Toporik ◽  
Zhen Da ◽  
...  
Keyword(s):  
Photosystem I ◽  
Light Harvesting ◽  
Higher Plants ◽  
Algal Species ◽  
Low Light ◽  
Light Harvesting Complex ◽  
Light Harvesting Complex Ii ◽  
Ancient Plants ◽  
Colonization Of Land ◽  
Green Lineage

The moss Physcomitrium patens diverged from green algae shortly after the colonization of land by ancient plants. This colonization posed new environmental challenges which drove evolutionary processes. The photosynthetic machinery of modern flowering plants is adapted to the high light conditions on land. Red shifted Lhca4 antennae are present in the photosystem I light harvesting complex of many green lineage plants but absent from P. patens. The Cryo-EM structure of the P. patens photosystem I light harvesting complex I supercomplex (PSI-LHCI) at 2.8 Å reveals that Lhca4 is replaced by a unique Lhca2 paralogue in moss. This PSI-LHCI supercomplex also retains the PsaM subunit, present in cyanobacteria and several algal species but lost in higher plants, and the PsaO subunit responsible for binding light harvesting complex II. The blue shifted Lhca2 paralogue and chlorophyll b enrichment relative to higher plants make the P. patens PSI-LHCI spectroscopically unique among other green lineage supercomplexes. Overall, the structure represents an evolutionary intermediate PSI with the crescent shaped LHCI common in higher plants and contains a unique Lhca2 paralogue which facilitates the mosses adaptation to low light niches.

Kinetics and heterogeneity of energy transfer from light harvesting complex II to photosystem I in the supercomplex isolated from Arabidopsis

2017 ◽  
Vol 19 (13) ◽  
pp. 9210-9222 ◽  
Author(s):  
Stefano Santabarbara ◽  
Tania Tibiletti ◽  
William Remelli ◽  
Stefano Caffarri
Keyword(s):  
Energy Transfer ◽  
Photosystem I ◽  
Light Harvesting ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Energy transfer from the LHCII when associated with the PSI–LHCI is heterogeneous and characterised by macroscopic transfer of ∼55 ns−1 and 15 ns−1, respectively.

Sign in / Sign up

Export Citation Format

Share Document