THE CHLOROPHYLL-CAROTENOID PROTEINS OF OXYGENIC PHOTOSYNTHESIS

The chlorophyll-carotenoid binding proteins responsible for absorption and conversion of light energy in oxygen-evolving photosynthetic orga nisms belong to two extended families: the Chl a binding core complexe s common to cyanobacteria and all chloroplasts, and the nuclear-encode d light-harvesting antenna com plexes of eukaryotic photosynthesizers (Chl a/b, Chl a/c, and Chl a proteins). There is a general consensus o n polypeptide and pigment composition for higher plant pigment protein s. These are reviewed and compared with pigment proteins of chlorophyt e, rhodophyte, and chromophyte algae. Major advances have been the det ermination of the structures of LHCII (major Chl a/b complex of higher plants), cyanobacterial Photosystem I, and the peridinen-Chl a protei n of dinoflagellates to atomic resolution. Better isolation methods, i mproved transformation procedures, and the availability of molecular s tructure models are starting to provide insights into the pathways of energy transfer and the macromolecular organization of thylakoid membr anes.