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| Abstract Title:
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| Energy transfer pathways in light harvesting systems templated by the Tobacco Mosaic Virus coat protein
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| Graduate Student Presenter:
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Rebekah Miller
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| Name of the Author(s) and Affiliation(s):
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Rebekah A. Miller, University of California, Berkeley; Andrew Preseley, University of California, Berkeley; Ying-Zhong Ma, University of California, Berkeley; and Matthew Francis, University of California, Berkeley
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Light harvesting (LH) systems in nature absorb light and transfer the energy to photosynthetic reaction centers, facilitating the formation of chemical bonds. The high efficiency of the natural system is achieved through a precisely spaced array of chromophores that can transport energy over long distances through a series of fluorescence resonance energy transfer (FRET) events. In the current study, we demonstrate that the tobacco mosaic virus coat protein (TMVP) can serve as a scaffold for the construction of highly efficient LH arrays. Recombinant C123 TMVP monomers were reacted with thiol-reactive chromophores before assembly into disk or rod assemblies. TEM anlaysis revealed that chromophore-bearing rods extend over hundreds of nanometers and contain 700 chromophores per 100 nm of rod length.
An attractive feature of this LH system is its capacity for donor-to-donor transfer events, which allow excitation energy from multiple donors to be conveyed over long distances toward a single acceptor molecule. Picosecond time-resolved fluorescence spectroscopy was used to characterize energy transfer between chromophores within rod assemblies of TMVP. To describe the pathways of energy transfer within this system, a global lifetime analysis was performed to obtain decay associated spectra. We found that energy transfer from donor to acceptor chromophores occurs in 187 ps with an efficiency of 36 %. A faster decay component of 70 ps is attributed to donor-to-donor transfer. Furthermore, studies of defect tolerance within these protein-based LH systems suggest that the rod assemblies are particularly resistant to defects.
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