title: Identification of a high-affinity phosphate transporter gene in a prasinophyte alga, Tetraselmis chui, and its expression under nutrient limitation.
abstract: A high-affinity phosphate transporter gene, TcPHO, was isolated from a growth-dependent subtracted cDNA library of the marine unicellular alga Tetraselmis chui. The full-length cDNA of TcPHO obtained by 5' and 3' rapid amplification of cDNA ends was 1,993 bp long and encoded an open reading frame consisting of 610 amino acids. The deduced amino acid sequence of TcPHO exhibited 51.6 and 49.8% similarity to the amino acid sequences of PHO89 from Saccharomyces cerevisiae and PHO4 from Neurospora crassa, respectively. In addition, hydrophobicity and secondary structure analyses revealed 12 conserved transmembrane domains that were the same as those found in PHO89 and PHO4. The expression of TcPHO mRNA was dependent on phosphate availability. With a low-phosphate treatment, the TcPHO mRNA concentration increased sharply to 2.72 fmol micro g of total RNA(-1) from day 1 to day 2 and remained at this high level from days 2 to 4. Furthermore, rescue treatment with either phosphate or p-nitrophenyl phosphate effectively inhibited TcPHO mRNA expression. In contrast, TcPHO mRNA expression stayed at a low level (range, 0.25 to 0.28 fmol micro g of total RNA(-1)) under low-nitrate conditions. The expression pattern suggests that TcPHO can be used as a molecular probe for monitoring phosphorus stress in T. chui.
authors.affiliation: Institute of Marine Biology, National Taiwan Ocean University, Keelung 20224, Taiwan, Republic of China.
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Chung
authors.forename: Sheng-Ping L
authors.initials: SP
authors.lastname: Hwang
authors.forename: Jeng
authors.initials: J
authors.lastname: Chang
mesh_terms: D020418:Algal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000460:Chlorophyta / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media; D005786:Gene Expression Regulation; D015723:Gene Library; D008969:Molecular Sequence Data; D028061:Phosphate Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010839:Phytoplankton / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D020418:Algal Proteins; D003470:Culture Media; D028061:Phosphate Transport Proteins; D010710:Phosphates; D012333:RNA, Messenger