title: Tapping the Unused Potential of Photosynthesis with a Heterologous Electron Sink.
abstract: Increasing the efficiency of the conversion of light energy to products by photosynthesis represents a grand challenge in biotechnology. Photosynthesis is limited by the carbon-fixing enzyme Rubisco resulting in much of the absorbed energy being wasted as heat or fluorescence or lost as excess reductant via alternative electron dissipation pathways. To harness this wasted reductant, we engineered the model cyanobacterium Synechococcus PCC 7002 to express the mammalian cytochrome P450 CYP1A1 to serve as an artificial electron sink for excess electrons derived from light-catalyzed water-splitting. This improved photosynthetic efficiency by increasing the maximum rate of photosynthetic electron flow by 31.3%. A simple fluorescent assay for CYP1A1 activity demonstrated that the P450 was functional in the absence of its native reductase, that activity was light-dependent and scaled with irradiance. We show for the first time in live cells that photosynthetic reductant can be redirected to power a heterologous cytochrome P450. Furthermore, Synechococcus PCC 7002 expressing CYP1A1 degraded the herbicide atrazine, which is a widespread environmental pollutant.
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre, University of Southampton , Southampton, United Kingdom.
authors.forename: Adokiye
authors.initials: A
authors.lastname: Berepiki
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hitchcock
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre, University of Southampton , Southampton, United Kingdom.
authors.forename: C Mark
authors.initials: CM
authors.lastname: Moore
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre, University of Southampton , Southampton, United Kingdom.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Bibby
mesh_terms: D000818:Animals; D001280:Atrazine / Q000737:chemistry; D001673:Biodegradation, Environmental; D003001:Cloning, Molecular; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism*; D004583:Electrons; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005818:Genetic Engineering; D006540:Herbicides / Q000737:chemistry; D008027:Light; D010788:Photosynthesis / Q000235:genetics*; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D046940:Synechococcus / Q000235:genetics* / Q000378:metabolism
chemical_list: D006540:Herbicides; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D019363:Cytochrome P-450 CYP1A1; D001280:Atrazine
keywords: P450; atrazine; cyanobacteria; electron sink; photosynthesis; photosystem