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

Reconstitution experiments o f light-harvesting complexes were performed with the green alga Chlorella fusca and the chlorophyll c-eontaining prasinophyte Mantoniella squamata using a modified method according to Plumley and Schmidt [Proc. Natl. Acad. Sei. U .S.A. 84, 146-150 (1987)]. Changing the pigment supply quantitatively or qualitatively in the reconsti­ tution 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 o f M. squamata polypeptides give further evidence for a rather high flexibility o f pigment recog­ nition and binding. This is the first report o f successful reconstitution o f a chlorophyll c-binding protein. Contrary to chlorophyll c-less light-harvesting complexes, the reconstitu­ tion o f M. squamata is strongly pH-controlled. In summary, the results give evidence for a high specificity o f porphyrin ring recognition and variability in xanthophyll binding capacity. Therefore, it is suggested that at least in algal light-harvesting proteins chlorophyll organiza­ tion may be determined by other mechanisms than xanthophyll binding.