title: Modification of energy-transfer processes in the cyanobacterium, Arthrospira platensis, to adapt to light conditions, probed by time-resolved fluorescence spectroscopy.
abstract: In cyanobacteria, the interactions among pigment-protein complexes are modified in response to changes in light conditions. In the present study, we analyzed excitation energy transfer from the phycobilisome and photosystem II to photosystem I in the cyanobacterium Arthrospira (Spirulina) platensis. The cells were grown under lights with different spectral profiles and under different light intensities, and the energy-transfer characteristics were evaluated using steady-state absorption, 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. The direct energy transfer from the phycobilisome to photosystem I and energy transfer from photosystem II to photosystem I were modified depending on the light quality, light quantity, and cultivation period. However, the total amount of energy transferred to photosystem I remained constant under the different growth conditions. We discuss the differences in energy-transfer processes under different cultivation and light conditions.
authors.affiliation: Molecular Photoscience Research Center, Kobe University, Kobe, 657-8501, Japan, akimoto@hawk.kobe-u.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Akimoto
authors.forename: Makio
authors.initials: M
authors.lastname: Yokono
authors.forename: Shimpei
authors.initials: S
authors.lastname: Aikawa
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D000042:Absorption; D000222:Adaptation, Physiological / Q000528:radiation effects*; D000458:Cyanobacteria / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D004735:Energy Transfer; D008027:Light; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex