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Tapping the Unused Potential of Photosynthesis with a Heterologous Electron Sink
journal contribution
posted on 2016-07-20, 00:00 authored by Adokiye Berepiki, Andrew Hitchcock, C. Mark Moore, Thomas S. BibbyIncreasing 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.
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heterologous cytochrome P 450.model cyanobacterium Synechococcus PCC 7002Heterologous Electron SinkSynechococcus PCC 7002P 450light energyherbicide atrazinePhotosynthesiphotosynthetic efficiencycytochrome P 450 CYP 1ACYP 1ACYP 1A activityphotosynthetic reductantalternative electron dissipation pathwaysphotosynthetic electron flow
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