The structure of purple bacterial antenna complexes: From single molecules to native membranes

The photosynthetic unit of purple photosynthetic bacteria typically contains two types of light-harvesting complexes, called LH1 and LH2. These antenna complexes are constructed on a modular principle. They are circular or elliptical oligomers of dimers of two low-molecular weight, hydrophobic apoproteins, called a and b, that bind bacteriochlorophylls and carotenoids non-covalently. The LH1 complex surrounds the reaction centre and, depending on the species, is either a monomer or a dimer. The LH2 complexes are arranged around the LH1-RC complexes. This plenary lecture will present the current status of structural studies on these pigment-protein complexes, based upon a combination of X-ray crystallography and single molecule spectroscopy. Then an overall view of how they are arranged in their native photosynthetic membranes will be presented