Mechanism of the Down Regulation of Photosynthesis by Blue Light in the Cyanobacterium Synechocystis sp. PCC 6803

作者：Matt Scott, Chantal McCollum, Sergej Vasil’ev, Cheryl Crozier, George S. Espie, Marianna Król, N. P. A. Hüner, Doug Bruce · 发表于：Biochemistry · 年份：2006 · DOI：10.1021/bi060767p · 被引用次数：93 · 研究领域：Photosynthetic Processes and Mechanisms、Algal biology and biofuel production、Photoreceptor and optogenetics research

Exposure to blue light has previously been shown to induce the reversible quenching of fluorescence in cyanobacteria, indicative of a photoprotective mechanism responsible for the down regulation of photosynthesis. We have investigated the molecular mechanism behind fluorescence quenching by characterizing changes in excitation energy transfer through the phycobilin pigments of the phycobilisome to chlorophyll with steady-state and time-resolved fluorescence excitation and emission spectroscopy. Quenching was investigated in both a photosystem II-less mutant, and DCMU-poisoned wild-type Synechocystis sp. PCC 6803. The action spectra for blue-light-induced quenching was identical in both cell types and was dominated by a band in the blue region, peaking at 480 nm. Fluorescence quenching and its dark recovery was inhibited by the protein cross-linking agent glutaraldehyde, which could maintain cells in either the quenched or the unquenched state. We found that high phosphate concentrations that inhibit phycobilisome mobility and the regulation of energy transfer by the light-state transition did not affect blue-light-induced fluorescence quenching. Both room temperature and 77 K fluorescence emission spectra revealed that fluorescence quenching was associated with phycobilin emission. Quenching was characterized by a decrease in the emission of allophycocyanin and long wavelength phycobilisome terminal emitters relative to that of phycocyanin. A global analysis of the room-temp...