In a study of the molecular mechanisms by which plants protect themselves from oxidation damage should they absorb too much sunlight during photosynthesis, a team of researchers has discovered a molecular dimmer switch that helps control the flow of solar energy moving through the system of light harvesting proteins. This discovery holds important implications for the future design of artificial photosynthesis systems that could provide the world with a sustainable and secure source of energy.
The pigment-binding protein CP29, one of the minor light-harvesting proteins in green plants, has been identified as a valve that permits or blocks the critical release of excess solar energy during photosynthesis. Furthermore, it has been proposed that the opening and closing of this valve can be controlled by raising or lowering ambient pH levels.
Graham Fleming, a physical chemist who holds joint appointments with the U.S. Department of Energys Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) at Berkeley, was one the leaders of this study, along with Krishna Niyogi, who also holds a joint appointment with Berkeley Lab and UC Berkeley, and Roberto Bassi, of the University of Verona, Italy.
This is really the first detailed picture ever obtained of the molecular mechanism behind the regulation of light harvesting energy, Fleming said. We believe we will soon be in position to build a complete model of the flow of energy through the photosynthetic light harvesting system that will include how the flow is controlled. This model could then be applied to the engineering of artificial versions of photosynthesis.
The results of this study are reported in the journal Science (May 9, 2008) in a paper entitled: Architecture of a Charge-Transfer State Regulating Light Harvesting in a Plant Antenna Protein. Co-authoring the paper with Fleming, Niyogi and Bassi were Tae Kyu Ahn, Thomas Avenson, Matteo Ba
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DOE/Lawrence Berkeley National Laboratory