Salt stress induces a decrease in excitation energy transfer from phycobilisomes to photosystem II but an increase to photosystem I in the cyanobacterium Spirulina platensis

2010 ◽  
Vol 167 (12) ◽  
pp. 951-958 ◽  
Author(s):  
Tao Zhang ◽  
Hongmei Gong ◽  
Xiaogang Wen ◽  
Congming Lu
Keyword(s):  
Energy Transfer ◽  
Salt Stress ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Photosystem I ◽  
Spirulina Platensis ◽  
Excitation Energy Transfer

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.

Cerulenin-Induced Modifications in the Fatty Acid Composition Affect Excitation Energy Transfer in Thylakoids of Petunia hybrida Leaves

1988 ◽  
Vol 43 (5-6) ◽  
pp. 431-437 ◽  
Author(s):  
Josef A. Graf ◽  
Karin Witzan ◽  
Reto J. Strasser
Keyword(s):  
Fatty Acid Composition ◽  
Energy Transfer ◽  
Fatty Acid ◽  
Photosystem Ii ◽  
Energy Distribution ◽  
Excitation Energy ◽  
Acid Composition ◽  
Petunia Hybrida ◽  
Excitation Energy Transfer ◽  
Acyl Lipids

Cerulenin-induced modifications in the fatty acid composition have been used to investigate the influence of acyl lipids on excitation energy distribution in thylakoid membranes of Petunia hybrida by means of 77 K fluorescence spectroscopy. Although cerulenin has no effect on relative contents of chlorophyll and acyl lipids, changes in the fatty acid composition of all thylakoid acyl lipids have been observed. The main cerulenin effect seems to be an increase in linoleic acid at the expense of saturated and monounsaturated C16- and C18-fatty acids resulting most likely in an increase in acyl lipid species containing both linoleic and linolenic acid. Low temperature (77 K ) fluorescence kinetics reveal a remarkable decrease in the ratio of the variable divided by the maximal fluorescence of photosystem II (F2(v)/F2(M)), taken as indicator for cerulenin-induced changes in this photosystem. Calculations of the excitation energy distribution terms based on a grouped bipartite model of photosynthesis suggest that a decrease in this ratio is caused by changes in energy transfer probabilities responsible for both, photochemical trapping of photosystem II and energetic cooperativity (grouping) between different photosystem II-light harvesting complex-units. Moreover, changes in the conformation responsible for spillover energy transfer are most likely to occur. Correlations between cerulenin-induced modifications of fatty acid composition and energy distribution support the assumption that excitation energy transfer depends on the structural state of the lipid matrix.

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 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.

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