ABSTRACT
We have identified a major 32 kDa protein in the dinoflagellate Gonyaulax polyedra as peridinin chlorophyll a-binding protein (PCP) based on microsequence data and immunological cross reaction with anti-PCP from another dinoflagellate species. A cDNA for this protein, identified by a PCR based cloning strategy, encoded 68 of the 68 amino acids microsequenced, thus confirming the identity of the clone. The PCP gene is highly expressed at both mRNA and protein level, and only PCP transcripts corresponding in size to the cDNA sequence were detected. Slot blot analyses show that there are roughly 5000 copies of the PCP gene in Gonyaulax, making this gene one of the most abundant protein coding genes ever reported, yet the sequence of the different gene copies in the genome appears extraordinarily well conserved by Southern blot analyses. The structure of the gene, addressed by Southern blots and PCR is suggested to be 5000 intronless coding sequences arranged head to tail in the genome separated by a conserved 1 kb spacer. Based on the conserved sequence of the spacer region, its presence next to each of the PCP coding sequences, and the uniform size of the PCP transcript, we propose that this region represents a dinoflagellate transcriptional promoter. This putative promoter region contains none of the DNA binding protein sequence elements involved in transcriptional initiation reported in other organisms.