Excitation energy transfer in the far-red absorbing violaxanthin/vaucheriaxanthin chlorophyll a complex from the eustigmatophyte alga FP5
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This work highlights spectroscopic investigations on a new representative of photosynthetic antenna complexes in the LHC family, a putative violaxanthin/vaucheriaxanthin chlorophyll a (VCP) antenna complex from a freshwater Eustigmatophyte alga FP5. A representative VCP-like complex, named as VCP-B3 was studied with both static and time-resolved spectroscopies with the aim of obtaining a deeper understanding of excitation energy migration within the pigment array of the complex. Compared to other VCP representatives, the absorption spectrum of the VCP-B3 is strongly altered in the range of the chlorophyll a Qy band, and is substantially red-shifted with the longest wavelength absorption band at 707 nm at 77 K. VCP-B3 shows a moderate xanthophyll-to-chlorophyll a efficiency of excitation energy transfer in the 50–60% range, 20–30% lower from comparable VCP complexes from other organisms. Transient absorption studies accompanied by detailed data fitting and simulations support the idea that the xanthophylls that occupy the central part of the complex, complementary to luteins in the LHCII, are violaxanthins. Target analysis suggests that the primary route of xanthophyll-to-chlorophyll a energy transfer occurs via the xanthophyll S1 state.
KeywordsTransient absorption Vaucheriaxanthin Light-harvesting complex Photosynthesis Chlorophyll a Violaxanthin
Decay-associated difference spectra
Evolution-associated difference spectra
Efficiency of excitation energy transfer
Excited state absorption
Full width at half maximum
High-performance liquid chromatography
Species-associated difference spectra
Violaxanthin/vaucheriaxanthin chlorophyll a-(band 3)
Steady-state and time-resolved spectroscopic studies were performed in the Ultrafast Laser Facility of the Photosynthetic Antenna Research Center (PARC), an Energy Frontier Research Center (EFRC) funded by Grant #DE-SC 0001035. Benjamin M. Wolf was supported by the William H. Danforth Plant Science Fellowship.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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