Characterization of centrin genes fromOchromonas danica(Chrysophyceae) andScytosiphon lomentaria(Phaeophyceae).

Centrin, the EF-hand Ca2+-binding protein is localized at the basal apparatus of flagella and in centrioles in many eukaryotic cells. In the present study, centrin genes of the heterokont algae have been clarified for the first time. We isolated and analyzed cDNA and genomic DNA of centrin genes from the crysophycean algaOchromonas danicaPrings (UTEX LB1298) and the brown algaScytosiphon lomentaria(Lyngbye) Link. The centrin gene ofOchromonascontained an open reading frame of 163 amino acids. The deduced protein, named Odcen, exhibited 85%, 78% and 59% homology toChlamydomonas, human andArabidopsiscentrin, respectively. The centrin genes ofScytosiphoncontained an open reading frame of 164 amino acids. The deduced protein, named Slcen, exhibited 84%, 77% and 59% homology toChlamydomonas, human andArabidopsiscentrin, respectively. Both Odcen and Slcen possessed N-terminal extensions before the conserved amino acid among various centrins, four EF-hand domains and an aromatic amino acid at the C-terminus. Southern blot hybridization suggested that the centrin gene occurs as a single copy gene in bothOchromonasandScytosiphongenomes. Comparison of the sequence of the cDNA and the genomic DNA revealed that the Odcen gene was split into three fragments by introns and Slcen gene consisted of five fragments. The junctions of all introns of both genes conformed to the GT-AG rule. The introns of Slcen gene were considerably long and, as a result, the Slcen gene was approximately seven times longer than Odcen gene. [ABSTRACT FROM AUTHOR]