Download MendeleyX-Ray Structure of the High-Salt Form of the Peridinin-Chlorophyll A-Protein from the Dinoflagellate Amphidinium Carterae: Modulation of the Spectral Properties of Pigments by the Protein Environment.
Schulte, T., Sharples, F.P., Hiller, R.G., Hofmann, E.(2009) Biochemistry 48: 4466
- PubMed: 19371099
- DOI: https://doi.org/10.1021/bi802320q
- Primary Citation of Related Structures:
2C9E - PubMed Abstract:
Light-harvesting complexes have evolved into very different structures but fulfill the same function, efficient harvesting of solar energy. In these complexes, pigments are fine-tuned and properly arranged to gather incoming photons. In the photosynthetic dinoflagellate Amphidinium carterae, two variants of the soluble light-harvesting complex PCP have been found [main form PCP (MFPCP) and high-salt PCP (HSPCP)], which show small variations in their pigment arrangement and tuning mechanisms. This feature makes them ideal models for studying pigment-protein interactions. Here we present the X-ray structure of the monomeric HSPCP determined at 2.1 A resolution and compare it to the structure of trimeric MFPCP. Despite the high degree of structural similarity (rmsd C(alpha)-C(alpha) of 1.89 A), the sequence variations lead to a changed overall pigment composition which includes the loss of two carotenoid molecules and a dramatic rearrangement of the chlorophyll phytol chains and of internal lipid molecules. On the basis of a detailed structural comparison, we favor a macrocycle geometry distortion of the chlorophylls rather than an electrostatic effect to explain energetic splitting of the chlorophyll a Q(y) bands [Ilagan, R. P. (2006) Biochemistry 45, 14052-14063]. Our analysis supports their assignment of peridinin 611* as the single blue-shifted peridinin in HSPCP but also highlights another electrostatic feature due to glutamate 202 which could add to the observed binding site asymmetry of the 611*/621* peridinin pair.
Organizational Affiliation:
Biophysics, Department of Biology and Biotechnology, Ruhr-University Bochum, D-44780 Bochum, Germany.
