As a model of photosynthetic unit (PSU), self-assembled aggregates of pigmentprotein complexes from photosynthetic bacteria were prepared in a lipid bilayer by reconstitution of the light-harvesting 2 (LH2) complex and light-harvesting 1reaction center (LH1RC) complex through detergent removal of their micelles in the presence of lipids. By performing polarization-controlled fluorescence and fluorescence-excitation spectroscopy on single aggregates at a temperature of 5 K, the composition of individual aggregates was determined and excitation energy transfer (EET) between constituent complexes was observed. LH2 and LH1RC from a bacterium, Rhodobacter (Rb.) sphaeroides, were found to form a trimeric aggregate in which EET takes place from one LH2 to two LH1RCs. In contrast, a heterodimer of LH2 and LH1RC in which EET works was found to assemble from a combination of complexes of different bacterial species, that is, LH2 from Rb. sphaeroides and LH1RC from Rhodopseudomonas (Rps.) palustris.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry