title: The Photosystem II D1-K238E mutation enhances electrical current production using cyanobacterial thylakoid membranes in a bio-photoelectrochemical cell.
abstract: The conversion of solar energy (SEC) to storable chemical energy by photosynthesis has been performed by photosynthetic organisms, including oxygenic cyanobacteria for over 3 billion years. We have previously shown that crude thylakoid membranes from the cyanobacterium Synechocytis sp. PCC 6803 can reduce the electron transfer (ET) protein cytochrome c even in the presence of the PSII inhibitor DCMU. Mutation of lysine 238 of the Photosystem II D1 protein to glutamic acid increased the cytochrome reduction rates, indicating the possible position of this unknown ET pathway. In this contribution, we show that D1-K238E is rather unique, as other mutations to K238, or to other residues in the same vicinity, are not as successful in cytochrome c reduction. This observation indicates the sensitivity of ET reactions to minor changes. As the next step in obtaining useful SEC from biological material, we describe the use of crude Synechocystis membranes in a bio-photovoltaic cell containing an N-acetyl cysteine-modified gold electrode. We show the production of significant current for prolonged time durations, in the presence of DCMU. Surprisingly, the presence of cytochrome c was not found to be necessary for ET to the bio-voltaic cell.
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Shirley
authors.initials: S
authors.lastname: Larom
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Faculty of Material Science and Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Kallmann
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Faculty of Material Science and Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Gadiel
authors.initials: G
authors.lastname: Saper
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Grand Technion Energy Program, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Faculty of Material Science and Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.|Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Roy
authors.initials: R
authors.lastname: Pinhassi
authors.affiliation: Faculty of Material Science and Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Avner
authors.initials: A
authors.lastname: Rothschild
authors.affiliation: Faculty of Material Science and Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Hen
authors.initials: H
authors.lastname: Dotan
authors.affiliation: Photovoltaics Lab, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Ankonina
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel. gadis@tx.technion.ac.il.
authors.forename: Gadi
authors.initials: G
authors.lastname: Schuster
authors.affiliation: Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa, Israel. nadir@tx.technion.ac.il.
authors.forename: Noam
authors.initials: N
authors.lastname: Adir
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry; D001674:Bioelectric Energy Sources; D045304:Cytochromes c / Q000378:metabolism; D055664:Electrochemical Techniques; D004566:Electrodes; D006859:Hydrogen / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D045332:Photosystem II Protein Complex / Q000235:genetics* / Q000378:metabolism; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; C422369:photosystem II, psbA subunit; D006859:Hydrogen; D045304:Cytochromes c; D000111:Acetylcysteine
keywords: Cyanobacteria; Cytochrome c; Electrochemistry; Photosynthesis; Solar energy conversion