CHARACTERIZATION OF GENES ENCODING THE LIGHT-HARVESTING PROTEINS IN DIATOMS - BIOGENESIS OF THE FUCOXANTHIN CHLOROPHYLL-A/C PROTEIN COMPLEX

In chromophytic algae the major light-harvesting complex is the fucoxanthin chlorophyll alc protein complex. Recently, we have cloned several highly related cDNA and genomic sequences encoding the fucoxanthin chlorophyll a/c proteins from the diatom Phaeodactylum tricornutum. These genes are clustered on the nuclear genome. The sequences of the fucoxanthin chlorophyll a/c proteins as deduced from the gene sequences have some similarity to the chlorophyll a/b proteins associated with light-harvesting complexes of higher plants and green algae. Like the chlorophyll a/b proteins of higher plants, the fucoxanthin chlorophyll a/c proteins are synthesized as higher-molecular weight precursors in the cytoplasm of the cell and are transported into the plastids. However, the mode of transport into diatom plastids is very different from the mechanism involved in transporting proteins into the chloroplasts of higher plants and green algae. We focus here on the characteristics of the fucoxanthin chlorophyll alc proteins, the mode of transport of these proteins into plastids, the arrangement of the genes encoding these proteins, and efforts to utilize these genes to develop a DNA transformation system for diatoms.