6533b873fe1ef96bd12d4a87

RESEARCH PRODUCT

Reconstitution of Light-Harvesting Complexes from Chlorella fusca (Chlorophyceae) and Mantoniella squamata (Prasinophyceae)

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Abstract Reconstitution experiments of light-harvesting complexes were performed with the green alga Chlorella fusca and the chlorophyll c-containing prasinophyte Mantoniella squamata using a modified method according to Plumley and Schmidt [Proc. N atl. Acad. Sei. U .S.A . 84, 146 -150 (1987)]. Changing the pigment supply quantitatively or qualitatively in the reconsti­tution mixture homologous and heterologous reconstitutes were obtained. In contrast to higher plants, light-harvesting polypeptides from green algae are able to bind the chlorophylls as well as the xanthophylls in different stoichiometries. Heterologous reconstitutes of M . squamata polypeptides give further evidence for a rather high flexibility of pigment recog­nition and binding. This is the first report of successful reconstitution of a chlorophyll c-binding protein. Contrary to chlorophyll c-less light-harvesting complexes, the reconstitution of M . squamata is strongly pH-controlled. In summary, the results give evidence for a high specificity of porphyrin ring recognition and variability in xanthophyll binding capacity. Therefore, it is suggested that at least in algal light-harvesting proteins chlorophyll organiza­tion may be determined by other mechanisms than xanthophyll binding.