The Dunaliella Sodium / Phosphorus Cotransporter Channel Gene And Glyceraldehyde-3 - Phosphate Dehydrogenase Gene Isolation And Analysis

Two sodium-dependent phosphate transporter cDNAs, DsSPT1 and DsSPT2, were isolated from the cDNA library of D. salina by using a SSH cDNA fragments A60 and CP1F1 as probes. The full-length cDNA was 2649bp and 2586bp long and encoded an open reading frame consisting of 672 and 675 amino acids, respectively. The deduced amino acid sequence of DsSPT1 and DsSPT2 exhibited 31.2% and 29.6% identities to the amino acid sequences of TcPHO from Tetraselmis chui. TM prediction revealed that there were 11 conserved transmembrane domains which were similar to those found in PHO89 and PHO4 from Saccharomyces cerevisiae and Neurospora crassa, respectively. Northern analyses indicated that transcripts level of DsSPT1 and DsSPT2 were induced under hyperosmotic stress and phosphate depletion. Southern analysis indicated that there were at least two inorganic phosphate transporter genes in the genome of D. salina. Promoter analysis of GDsSPT1 revealed there was a stress responsive cis-elements (CACGT) in the promoter region (-711～-715bp). Southern analysis indicated that there were at least two phosphate transporter genes in the whole genome of D. salina. DsSPT1 and DsSPT2 generated hypersensitivity to sodium in a salt-sensitive yeast strain G19, which was disrupted in the genes encoding Na+ export pumps. In conclusion, we have firstly isolated two differential expressed sodium-dependent phosphate transporter cDNAs from Dunaliella salina.