SANS investigation of the photosynthetic machinery of Chloroflexus aurantiacus
Green photosynthetic bacteria harvest light and perform photosynthesis in low-light environments, and contain specialized antenna complexes to adapt to this condition. We performed small-angle neutron scattering (SANS) studies to obtain structural information about the photosynthetic apparatus, including the peripheral light-harvesting chlorosome complex, the integral membrane light-harvesting B808-866 complex, and the reaction center (RC) in the thermophilic green phototrophic bacterium Chloroflexus aurantiacus. Using contrast variation in SANS measurements, we found that the B808-866 complex is wrapped around the RC in Cfx. aurantiacus, and the overall size and conformation of the B808-866 complex of Cfx. aurantiacus is roughly comparable to the LH1 antenna complex of the purple bacteria. A similar size of the isolated B808-866 complex was suggested by dynamic light scattering measurements, and a smaller size of the RC of Cfx. aurantiacus compared to the RC of the purple bacteria was observed. Further, our SANS measurements indicate that the chlorosome is a lipid body with a rod-like shape, and that the self-assembly of bacteriochlorophylls, the major component of the chlorosome, is lipid-like. Finally, two populations of chlorosome particles are suggested in our SANS measurements.
- Research Organization:
- Energy Frontier Research Centers (EFRC); Photosynthetic Antenna Research Center (PARC)
- Sponsoring Organization:
- USDOE SC Office of Basic Energy Sciences (SC-22)
- DOE Contract Number:
- SC0001035
- OSTI ID:
- 1065281
- Journal Information:
- Biophys. J., Journal Name: Biophys. J. Vol. 99
- Country of Publication:
- United States
- Language:
- English
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