scholarly journals Structural insights into an evolutionary turning-point of photosystem I from prokaryotes to eukaryotes

2022 ◽  
Author(s):  
Koji Kato ◽  
Ryo Nagao ◽  
Yoshifumi Ueno ◽  
Makio Yokono ◽  
Takehiro Suzuki ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Photosystem I ◽  
Turning Point ◽  
Excitation Energy Transfer ◽  
Microscopic Structure ◽  
Cyanophora Paradoxa ◽  
Electron Microscopic ◽  
Photosynthetic Organisms ◽  
Structural Insights

Photosystem I (PSI) contributes to light-conversion reactions; however, its oligomerization state is variable among photosynthetic organisms. Herein we present a 3.8-Å resolution cryo-electron microscopic structure of tetrameric PSI isolated from a glaucophyte alga Cyanophora paradoxa. The PSI tetramer is organized in a dimer of dimers form with a C2 symmetry. Different from cyanobacterial PSI tetramer, two of the four monomers are rotated around 90°, resulting in a totally different pattern of monomer-monomer interactions. Excitation-energy transfer among chlorophylls differs significantly between Cyanophora and cyanobacterial PSI tetramers. These structural and spectroscopic features reveal characteristic interactions and energy transfer in the Cyanophora PSI tetramer, thus offering an attractive idea for the changes of PSI from prokaryotes to eukaryotes.

scholarly journals Structure of a cyanobacterial photosystem I surrounded by octadecameric IsiA antenna proteins

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Fusamichi Akita ◽  
Ryo Nagao ◽  
Koji Kato ◽  
Yoshiki Nakajima ◽  
Makio Yokono ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Photosystem I ◽  
Fluorescence Spectra ◽  
Protein A ◽  
Excitation Energy Transfer ◽  
Electron Microscopic ◽  
Time Resolved ◽  
Closed Ring ◽  
Membrane Spanning

AbstractIron-stress induced protein A (IsiA) is a chlorophyll-binding membrane-spanning protein in photosynthetic prokaryote cyanobacteria, and is associated with photosystem I (PSI) trimer cores, but its structural and functional significance in light harvesting remains unclear. Here we report a 2.7-Å resolution cryo-electron microscopic structure of a supercomplex between PSI core trimer and IsiA from a thermophilic cyanobacterium Thermosynechococcus vulcanus. The structure showed that 18 IsiA subunits form a closed ring surrounding a PSI trimer core. Detailed arrangement of pigments within the supercomplex, as well as molecular interactions between PSI and IsiA and among IsiAs, were resolved. Time-resolved fluorescence spectra of the PSI–IsiA supercomplex showed clear excitation-energy transfer from IsiA to PSI, strongly indicating that IsiA functions as an energy donor, but not an energy quencher, in the supercomplex. These structural and spectroscopic findings provide important insights into the excitation-energy-transfer and subunit assembly mechanisms in the PSI–IsiA supercomplex.

scholarly journals LHCSR1-dependent fluorescence quenching is mediated by excitation energy transfer from LHCII to photosystem I in Chlamydomonas reinhardtii

2018 ◽  
Vol 115 (14) ◽  
pp. 3722-3727 ◽  
Author(s):  
Kotaro Kosuge ◽  
Ryutaro Tokutsu ◽  
Eunchul Kim ◽  
Seiji Akimoto ◽  
Makio Yokono ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Photosystem Ii ◽  
Fluorescence Quenching ◽  
Excitation Energy ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Excitation Energy Transfer ◽  
High Light ◽  
Light Harvesting Complexes ◽  
Photosynthetic Organisms

Photosynthetic organisms are frequently exposed to light intensities that surpass the photosynthetic electron transport capacity. Under these conditions, the excess absorbed energy can be transferred from excited chlorophyll in the triplet state (3Chl*) to molecular O2, which leads to the production of harmful reactive oxygen species. To avoid this photooxidative stress, photosynthetic organisms must respond to excess light. In the green alga Chlamydomonas reinhardtii, the fastest response to high light is nonphotochemical quenching, a process that allows safe dissipation of the excess energy as heat. The two proteins, UV-inducible LHCSR1 and blue light-inducible LHCSR3, appear to be responsible for this function. While the LHCSR3 protein has been intensively studied, the role of LHCSR1 has been only partially elucidated. To investigate the molecular functions of LHCSR1 in C. reinhardtii, we performed biochemical and spectroscopic experiments and found that the protein mediates excitation energy transfer from light-harvesting complexes for Photosystem II (LHCII) to Photosystem I (PSI), rather than Photosystem II, at a low pH. This altered excitation transfer allows remarkable fluorescence quenching under high light. Our findings suggest that there is a PSI-dependent photoprotection mechanism that is facilitated by LHCSR1.

pH-Induced Regulation of Excitation Energy Transfer in the Cyanobacterial Photosystem I Tetramer

2020 ◽  
Vol 124 (10) ◽  
pp. 1949-1954 ◽  
Author(s):  
Ryo Nagao ◽  
Makio Yokono ◽  
Yoshifumi Ueno ◽  
Tian-Yi Jiang ◽  
Jian-Ren Shen ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Photosystem I ◽  
Excitation Energy Transfer

scholarly journals The structure of plant photosystem I super-complex at 2.8 Å resolution

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Yuval Mazor ◽  
Anna Borovikova ◽  
Nathan Nelson
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Photosystem I ◽  
Excitation Energy Transfer ◽  
Life Forms ◽  
Reaction Centers ◽  
Oxygenic Photosynthesis ◽  
Chlorophyll B ◽  
Higher Plant ◽  
Prosthetic Groups

Most life forms on Earth are supported by solar energy harnessed by oxygenic photosynthesis. In eukaryotes, photosynthesis is achieved by large membrane-embedded super-complexes, containing reaction centers and connected antennae. Here, we report the structure of the higher plant PSI-LHCI super-complex determined at 2.8 Å resolution. The structure includes 16 subunits and more than 200 prosthetic groups, which are mostly light harvesting pigments. The complete structures of the four LhcA subunits of LHCI include 52 chlorophyll a and 9 chlorophyll b molecules, as well as 10 carotenoids and 4 lipids. The structure of PSI-LHCI includes detailed protein pigments and pigment–pigment interactions, essential for the mechanism of excitation energy transfer and its modulation in one of nature's most efficient photochemical machines.

Excitation Energy Transfer in the Lhca1 Subunit of LHC I-730 Peripheral Antenna of Photosystem I

2002 ◽  
Vol 106 (16) ◽  
pp. 4313-4317 ◽  
Author(s):  
Alexander N. Melkozernov ◽  
Volkmar H. R. Schmid ◽  
Su Lin ◽  
Harald Paulsen ◽  
Robert E. Blankenship
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Photosystem I ◽  
Excitation Energy Transfer ◽  
Lhc I
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