Absorption of sunlight is the first step in photosynthesis, which provides energy for the vast majority of organisms on Earth. The primary processes of photosynthesis have been studied extensively in isolated light-harvesting complexes and reaction centres, however, to understand fully the way in which organisms capture light it is crucial to also reveal the functional relationships between the individual complexes.
In this project we reported the use of two-dimensional electronic spectroscopy to track directly the excitation-energy flow through the entire photosynthetic system of green sulfur bacterium - an assembly of light-harvesting complexes, a chlorosome (aggregated bacteriochlorophyll c (BChl) molecules and a baseplate of pigment-protein complex containing BChsl a and carotenoids), Fenna-Matthews-Olson (FMO) proteins and reaction centers (RCs).
Obtained energy transfer pathways and energy transfer rates, which are summarized in the figure below, allowed us to determined how different parts of system of green sulfur bacteria are connected and to demonstrate that FMO serves as an energy conduit between the chlorosome and RCs.
- J. Dostál, J. Pšenčík, D. Zigmantas, In situ mapping of the energy flow through the entire photosynthetic apparatus. Nature Chem. 8, 705-710 (2016).