title: Regulating the Energy Flow in a Cyanobacterial Light-Harvesting Antenna Complex.
abstract: 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.
authors.affiliation: Applied Physics Department and The Center for Nano-Science and Nano-Technology, The Hebrew University of Jerusalem , Jerusalem 9190401, Israel.
authors.forename: Ido
authors.identifier: 0000-0003-3079-3235
authors.initials: I
authors.lastname: Eisenberg
authors.affiliation: Institute of Theoretical Physics, Ulm University , Albert Einstein Alle 11, 89069 Ulm, Germany.
authors.forename: Felipe
authors.initials: F
authors.lastname: Caycedo-Soler
authors.affiliation: Schulich Faculty of Chemistry, Technion - Israel Institute of Technology , Haifa 32000, Israel.
authors.forename: Dvir
authors.initials: D
authors.lastname: Harris
authors.affiliation: Applied Physics Department and The Center for Nano-Science and Nano-Technology, The Hebrew University of Jerusalem , Jerusalem 9190401, Israel.
authors.forename: Shira
authors.initials: S
authors.lastname: Yochelis
authors.affiliation: Institute of Theoretical Physics, Ulm University , Albert Einstein Alle 11, 89069 Ulm, Germany.
authors.forename: Susana F
authors.initials: SF
authors.lastname: Huelga
authors.affiliation: Institute of Theoretical Physics, Ulm University , Albert Einstein Alle 11, 89069 Ulm, Germany.
authors.forename: Martin B
authors.initials: MB
authors.lastname: Plenio
authors.affiliation: Schulich Faculty of Chemistry, Technion - Israel Institute of Technology , Haifa 32000, Israel.
authors.forename: Noam
authors.initials: N
authors.lastname: Adir
authors.affiliation: Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem , Givat Ram, Jerusalem 9190401, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Keren
authors.affiliation: Applied Physics Department and The Center for Nano-Science and Nano-Technology, The Hebrew University of Jerusalem , Jerusalem 9190401, Israel.
authors.forename: Yossi
authors.initials: Y
authors.lastname: Paltiel
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry / Q000378:metabolism*; D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism*; D008163:Luminescent Measurements; D008958:Models, Molecular
chemical_list: D045342:Light-Harvesting Protein Complexes