Jen Hsin, Johan Strümpfer, Melih Sener, Pu Qian, C. Neil Hunter, and Klaus Schulten. Energy transfer dynamics in an RC-LH1-PufX tubular photosynthetic membrane. New Journal of Physics, 12:085005, 2010. (19 pages). (PMC: 2997751)

HSIN2010A Light absorption and the subsequent transfer of excitation energy are the first two steps of the photosynthetic process, carried out by the protein-bound pigments, bacteriochlorophylls (BChls), in photosynthetic bacteria. BChls are anchored in light- harvesting (LH) complexes, such as the light-harvesting complex I (LH1), which directly associates with the reaction center (RC), forming the RC-LH1 core complex. In Rhodobacter sphaeroides, RC-LH1 core complexes contain an additional protein, PufX, and assemble into dimeric RC-LH1-PufX core complexes. In the absence of light- harvesting complexes II, these complexes can aggregate into a helically ordered tubular photosynthetic membrane. We examined the excitation transfer dynamics in a single RC- LH1-PufX core complex dimer using the hierarchical equations of motion for dissipative quantum dynamics that accurately treat the coupling between BChls and their protein environment. Generalized Förster theory was also used to calculate the transfer rates of the same excitonic system. Additionally, in light of the structural uncertainties in the Rhodobacter sphaeroides RC-LH1-PufX core complex, geometrical alterations were introduced in the BChl organization. It is shown that the energy transfer dynamics is not affected by the considered changes in the BChl organization, and that generalized Förster theory provides accurate transfer rates. An all-atom model for a tubular photosynthetic membrane is constructed, and the overall energy transfer properties of this membrane are computed.


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