Photosynthetic Membranes of Synechocystis or Plants Convert Sunlight to Photocurrent through Different Pathways due to Different Architectures.
Thylakoid membranes contain the redox active complexes catalyzing the light-dependent reactions of photosynthesis in cyanobacteria, algae and plants. Crude thylakoid membranes or purified photosystems from different organisms have previously been utilized for generation of electrical power and/or fuels. Here we investigate the electron transferability from thylakoid preparations from plants or the cyanobacterium Synechocystis. We show that upon illumination, crude Synechocystis thylakoids can reduce cytochrome c. In addition, this crude preparation can transfer electrons to a graphite electrode, producing an unmediated photocurrent of 15 μA/cm2. Photocurrent could be obtained in the presence of the PSII inhibitor DCMU, indicating that the source of electrons is QA, the primary Photosystem II acceptor. In contrast, thylakoids purified from plants could not reduce cyt c, nor produced a photocurrent in the photocell in the presence of DCMU. The production of significant photocurrent (100 μA/cm2) from plant thylakoids required the addition of the soluble electron mediator DCBQ. Furthermore, we demonstrate that use of crude thylakoids from the D1-K238E mutant in Synechocystis resulted in improved electron transferability, increasing the direct photocurrent to 35 μA/cm2. Applying the analogous mutation to tobacco plants did not achieve an equivalent effect. While electron abstraction from crude thylakoids of cyanobacteria or plants is feasible, we conclude that the site of the abstraction of the electrons from the thylakoids, the architecture of the thylakoid preparations influence the site of the electron abstraction, as well as the transfer pathway to the electrode. This dictates the use of different strategies for production of sustainable electrical current from photosynthetic thylakoid membranes of cyanobacteria or higher plants.
Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Department of Science and Material Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Roy I
RI
Pinhassi
Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Department of Science and Material Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Dan
D
Kallmann
Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Department of Science and Material Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Gadiel
G
Saper
Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Shirley
S
Larom
Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Artyom
A
Linkov
Max-Planck-Institut für molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany.
Alix
A
Boulouis
Max-Planck-Institut für molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany.
Mark-Aurel
MA
Schöttler
Max-Planck-Institut für molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany.
Ralph
R
Bock
Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Department of Science and Material Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Avner
A
Rothschild
Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Noam
N
Adir
Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel; Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000 Israel.
Gadi
G
Schuster
D004566:Electrodes; D004579:Electron Transport / Q000502:physiology; D004583:Electrons; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D013472:Sunlight; D046939:Synechocystis / Q000378:metabolism / Q000502:physiology*; D020524:Thylakoids / Q000378:metabolism / Q000502:physiology*
D045332:Photosystem II Protein Complex