Carotenoids as Components of the Light-harvesting Proteins of Eukaryotic Algae

Abstract

Studies of light harvesting proteins which contain carotenoids as the principal components absorbing light in the spectral region from 450 nm to 550 nm have three principal aims. These may be summarized as: how do these proteins work at the structure/function level; how do they adapt to different environmental conditions and how did they evolve. At the structural level the emphasis has shifted, perhaps prematurely, from studies of pigment composition and basic biochemistry to a consideration of atomic structures and viewing carotenoids in action directly by means of time resolved spectroscopy. The only caroteno-Chl protein from eukaryotic algae for which a high resolution structrue is available is soluble peridinin chlorophyll a -protein (sPCP). PCP is the protein with the highest carotenoid:Chl ratio and has the potential to greatly advance our understanding of photosynthetic energy transfer through site directed mutagenesis and in vitro reconstitution from heterologously expressed protein and purified pigments.