Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 15: Postersession III

BP 15.51: Poster

Dienstag, 13. März 2018, 14:00–16:00, Poster B

Efficient coupling between phycobilisomes, chlorophyll a and far red light induced chlorophyll f in the cyanobacterium Halomicronema hongdechloris — •Züleyha Yenice Campbell, Franz-Josef Schmitt, Mai Vi Bui, and Thomas Friedrich — TU Berlin, Institut für Chemie, Bioenergetik, Deutschland

The excitation energy transfer processes in the antenna system of the phototrophic cyanobacterium Halomicronema hongdechloris that contains Chlorophyll a and f in photosystem II with red light induced accumulation of Chl f was investigated. While H. hongdechloris has only very low amounts of Chl f in white-light culture conditions the ratio of Chl f to Chl a is reversibly changed up to 1:8 under illumination with far red light (720-730 nm). We performed UV-Vis absorption spectroscopy, time-integrated and time-resolved fluorescence spectroscopy and calculated decay associated spectra (DAS) indicating that highly efficient EET occurs from phycobilisomes to Chl a with time constants of about 100 ps in white light. Charge separation occurs with a typical apparent kinetics of 200-300 ps from Chl a as known from Chl a containing cyanobacteria like Synechocystis sp. PCC 6803. In H. hongdechloris, maximal Chl f concentration was observed after 3-4 days of growth under far red light (720-730 nm) and EET from PBS reached Chl f within 200 ps. However, fast charge separation was not observed from Chl f. Therefore, it is proposed, based on modeling of possible rate equation systems of EET that the charge separation occurs from Chl a and excitation energy is funneled from Chl f to Chl a via an energetic uphill transfer mechanism.