Characterization of a cDNA encoding for the 28.5-kDa LHCII apoprotein from the unicellular marine chlorophyte, Dunaliella tertiolecta.

Three distinct clones, encoding light-harvesting chlorophyll (LHCII) proteins associated with photosystem II were isolated from a cDNA library of the unicellular marine chlorophyte, Dunaliella tertiolecta. We determined the nucleotide sequence of one of these clones, as well as the N-terminal amino acid (aa) sequences of the four mature LHCII apoproteins (24.5, 28.5, 30 and 31 kDa). The sequenced cDNA clone encoded the precursor of the 28.5-kDa apoprotein. We deduced that the transit peptide is 30 aa long and the mature protein is processed between A and V within the peptide RAAVEFYGP. Southern blots of D. tertiolecta genomic DNA indicated the presence of three to five genes. The algal aa sequence differs from higher plants mainly in the transit peptide and the N terminus. Several aa residues, highly conserved in higher plants, which are believed to play a role in chlorophyll binding, are not conserved in the chlorophytes.