Photosynthetic organisms harvest light energy, utilizing the absorption and energy-transfer properties of protein-bound chromophores. Controlling the harvesting efficiency is critical for the optimal function of the photosynthetic apparatus. Here, we show that the cyanobacterial light-harvesting antenna complex may be able to regulate the flow of energy to switch reversibly from efficient energy conversion to photoprotective quenching via a structural change. We isolated cyanobacterial light-harvesting proteins, phycocyanin and allophycocyanin, and measured their optical properties in solution and in an aggregated-desiccated state. The results indicate that energy band structures are changed, generating a switch between the two modes of operation, exciton transfer and quenching, achieved without dedicated carotenoid quenchers. This flexibility can contribute greatly to the large dynamic range of cyanobacterial light-harvesting systems. (Figure Presented).
Bibliographical noteFunding Information:
This research was supported by a grant no. 3-12405(151235) from the Ministry of Science, Technology and Space, Israel, the National Science Council (NSC) of Taiwan, the Israel Science Foundation (1576/12 and 843/16), the US-Israel Bi-National Science Fund (2014395), the ERC Synergy grant BioQ, the EU STREP project PAPETS, and an Alexander von Humboldt Professorship. We also want to thank Lior Bezen for her assistance in life-time measurements.
© 2017 American Chemical Society.