Structural Basis of Light Harvesting by Carotenoids: Peridinin-Chlorophyll-Protein from Amphidinium carterae

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Science  21 Jun 1996:
Vol. 272, Issue 5269, pp. 1788-1791
DOI: 10.1126/science.272.5269.1788


Peridinin-chlorophyll-protein, a water-soluble light-harvesting complex that has a blue-green absorbing carotenoid as its main pigment, is present in most photosynthetic dinoflagellates. Its high-resolution (2.0 angstrom) x-ray structure reveals a noncrystallographic trimer in which each polypeptide contains an unusual jellyroll fold of the α-helical amino- and carboxyl-terminal domains. These domains constitute a scaffold with pseudo-twofold symmetry surrounding a hydrophobic cavity filled by two lipid, eight peridinin, and two chlorophyll a molecules. The structural basis for efficient excitonic energy transfer from peridinin to chlorophyll is found in the clustering of peridinins around the chlorophylls at van der Waals distances.