Short-term light adaptation of a cyanobacterium, Synechocystis sp. PCC 6803, probed by time-resolved fluorescence spectroscopy.
In photosynthetic organisms, the interactions among pigment-protein complexes change in response to light conditions. In the present study, we analyzed the transfer of excitation energy from the phycobilisome (PBS) and photosystem (PS) II to PSI in the cyanobacterium Synechocystis sp. PCC 6803. After 20 min of dark adaptation, Synechocystis cells were illuminated for 5 min with strong light with different spectral profiles, blue, green, two kinds of red, and white light. After illumination, the energy-transfer characteristics were evaluated using steady-state fluorescence and picosecond time-resolved fluorescence spectroscopy techniques. The fluorescence rise and decay curves were analyzed by global analysis to obtain fluorescence decay-associated spectra, followed by spectral component analysis. Under illumination with strong light, the contribution of the energy transfer from the PSII to PSI (spillover) became greater, and that of the energy transfer from the PBS to PSI decreased; the former change was larger than the latter. The energy transfer pathway to PSI was sensitive to red light. We discuss the short-term adaptation of energy-transfer processes in Synechocystis under strong-light conditions.
Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan; Japan Science and Technology Agency, CREST, Kobe 657-8501, Japan. Electronic address: akimoto@hawk.kobe-u.ac.jp.
Seiji
S
Akimoto
Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan.
Makio
M
Yokono
Sapporo, Japan.
Erina
E
Yokono
Japan Science and Technology Agency, CREST, Kobe 657-8501, Japan; Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan.
Shimpei
S
Aikawa
Japan Science and Technology Agency, CREST, Kobe 657-8501, Japan; Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan.
Akihiko
A
Kondo
D000222:Adaptation, Physiological / Q000528:radiation effects*; D004579:Electron Transport; D004735:Energy Transfer; D008027:Light; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D052979:Phycobiliproteins / Q000378:metabolism; D045524:Phycobilisomes / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D046939:Synechocystis / Q000502:physiology* / Q000528:radiation effects; D013997:Time Factors
D045332:Photosystem II Protein Complex; D052979:Phycobiliproteins; D045524:Phycobilisomes
Delayed fluorescence; Energy transfer; Light adaptation; Phycobilisome