Excitation Energy Transfer and Quenching in Diatom PSI-FCPI Upon P700 Cation Formation

Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

Research output: Contribution to journalArticle

Abstract

Excitation-energy transfer in photosystem I (PSI) is changed by a cation formation of a special pair chlorophyll P700 in PSI core; however, it remains unclear how light-harvesting pigment-protein complexes are involved in the P700-related energy-transfer mechanisms. Here we report effects of the redox changes of P700 on excitation-energy dynamics in diatom PSI-fucoxanthin chlorophyll a/c-binding protein (PSI-FCPI) and PSI core complexes by means of time-resolved fluorescence (TRF) spectroscopy. For the TRF measurements, the PSI-FCPI and PSI were adapted under P700 neutral and cation conditions using chemical reagents. Upon the P700+ formation, fluorescence decay-associated (FDA) spectra constructed from the TRF spectra exhibit a larger fluorescence decay amplitude relative to a fluorescence rise magnitude within 100 ps in each of the PSI-FCPI and PSI. The decay components are shifted to lower wavelengths in each of the P700-cation PSI-FCPI and PSI than in the P700-neutral PSIs. The rapid fluorescence decays upon the P700+ formation are clearly verified by mean-lifetime spectra reconstructed from the FDA spectra. Since the P700-cation PSI does not cause charge-separation reactions, the relatively strong decay components and rapid fluorescence decays observed are likely attributed to excitation-energy quenching. These observations suggest that Chls in PSI and around/within FCPI are involved in the energy-quenching events by the redox changes of P700.

Original languageEnglish
JournalJournal of Physical Chemistry B
DOIs
Publication statusE-pub ahead of print - Feb 3 2020

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Photosystem I Protein Complex
Diatoms
Energy Transfer
Cations
Fluorescence
Oxidation-Reduction
Light-Harvesting Protein Complexes
Chlorophyll Binding Proteins
Fluorescence Spectrometry
Chlorophyll

Cite this

Excitation Energy Transfer and Quenching in Diatom PSI-FCPI Upon P700 Cation Formation. / Nagao, Ryo; Yokono, Makio; Ueno, Yoshifumi; Shen, Jian-Ren; Akimoto, Seiji.

In: Journal of Physical Chemistry B, 03.02.2020.

Research output: Contribution to journalArticle

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abstract = "Excitation-energy transfer in photosystem I (PSI) is changed by a cation formation of a special pair chlorophyll P700 in PSI core; however, it remains unclear how light-harvesting pigment-protein complexes are involved in the P700-related energy-transfer mechanisms. Here we report effects of the redox changes of P700 on excitation-energy dynamics in diatom PSI-fucoxanthin chlorophyll a/c-binding protein (PSI-FCPI) and PSI core complexes by means of time-resolved fluorescence (TRF) spectroscopy. For the TRF measurements, the PSI-FCPI and PSI were adapted under P700 neutral and cation conditions using chemical reagents. Upon the P700+ formation, fluorescence decay-associated (FDA) spectra constructed from the TRF spectra exhibit a larger fluorescence decay amplitude relative to a fluorescence rise magnitude within 100 ps in each of the PSI-FCPI and PSI. The decay components are shifted to lower wavelengths in each of the P700-cation PSI-FCPI and PSI than in the P700-neutral PSIs. The rapid fluorescence decays upon the P700+ formation are clearly verified by mean-lifetime spectra reconstructed from the FDA spectra. Since the P700-cation PSI does not cause charge-separation reactions, the relatively strong decay components and rapid fluorescence decays observed are likely attributed to excitation-energy quenching. These observations suggest that Chls in PSI and around/within FCPI are involved in the energy-quenching events by the redox changes of P700.",
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AU - Nagao, Ryo

AU - Yokono, Makio

AU - Ueno, Yoshifumi

AU - Shen, Jian-Ren

AU - Akimoto, Seiji

PY - 2020/2/3

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N2 - Excitation-energy transfer in photosystem I (PSI) is changed by a cation formation of a special pair chlorophyll P700 in PSI core; however, it remains unclear how light-harvesting pigment-protein complexes are involved in the P700-related energy-transfer mechanisms. Here we report effects of the redox changes of P700 on excitation-energy dynamics in diatom PSI-fucoxanthin chlorophyll a/c-binding protein (PSI-FCPI) and PSI core complexes by means of time-resolved fluorescence (TRF) spectroscopy. For the TRF measurements, the PSI-FCPI and PSI were adapted under P700 neutral and cation conditions using chemical reagents. Upon the P700+ formation, fluorescence decay-associated (FDA) spectra constructed from the TRF spectra exhibit a larger fluorescence decay amplitude relative to a fluorescence rise magnitude within 100 ps in each of the PSI-FCPI and PSI. The decay components are shifted to lower wavelengths in each of the P700-cation PSI-FCPI and PSI than in the P700-neutral PSIs. The rapid fluorescence decays upon the P700+ formation are clearly verified by mean-lifetime spectra reconstructed from the FDA spectra. Since the P700-cation PSI does not cause charge-separation reactions, the relatively strong decay components and rapid fluorescence decays observed are likely attributed to excitation-energy quenching. These observations suggest that Chls in PSI and around/within FCPI are involved in the energy-quenching events by the redox changes of P700.

AB - Excitation-energy transfer in photosystem I (PSI) is changed by a cation formation of a special pair chlorophyll P700 in PSI core; however, it remains unclear how light-harvesting pigment-protein complexes are involved in the P700-related energy-transfer mechanisms. Here we report effects of the redox changes of P700 on excitation-energy dynamics in diatom PSI-fucoxanthin chlorophyll a/c-binding protein (PSI-FCPI) and PSI core complexes by means of time-resolved fluorescence (TRF) spectroscopy. For the TRF measurements, the PSI-FCPI and PSI were adapted under P700 neutral and cation conditions using chemical reagents. Upon the P700+ formation, fluorescence decay-associated (FDA) spectra constructed from the TRF spectra exhibit a larger fluorescence decay amplitude relative to a fluorescence rise magnitude within 100 ps in each of the PSI-FCPI and PSI. The decay components are shifted to lower wavelengths in each of the P700-cation PSI-FCPI and PSI than in the P700-neutral PSIs. The rapid fluorescence decays upon the P700+ formation are clearly verified by mean-lifetime spectra reconstructed from the FDA spectra. Since the P700-cation PSI does not cause charge-separation reactions, the relatively strong decay components and rapid fluorescence decays observed are likely attributed to excitation-energy quenching. These observations suggest that Chls in PSI and around/within FCPI are involved in the energy-quenching events by the redox changes of P700.

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