2003 Fiscal Year Final Research Report Summary
Analysis of phosphate transporters which are related to arsenic resistance
| Project/Area Number |
13640657
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物生理
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| Research Institution | Tokyo University of Pharmacy and Life Science |
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Principal Investigator |
SHOKO Fujiwara Tokyo University of Pharmacy and Life Science, School of Life Science, Assistant Professor, 生命科学部, 講師 (30266895)
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| Co-Investigator(Kenkyū-buntansha) |
KAISE Toshikazu Tokyo University of Pharmacy and Life Science, School of Life Science, Professor, 生命科学部, 教授 (20266894)
TSUZUKI Mikio Tokyo University of Pharmacy and Life Science, School of Life Science, Professor, 生命科学部, 教授 (70155430)
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| Project Period (FY) |
2001 – 2003
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| Keywords | arsenic resistance / phosphate transporter / arsenate / Chlamydomonas / green alga |
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| Research Abstract |
An arsenate-resistant mutant AR3 of Chlamydomonas reinhardtii is a recessive mutant generated by random insertional mutagenesis using the ARG7 gene. AR3 shows about 10-fold resistance against arsenate toxicity compared with the wild type. By using a flanking region of an inserted tag as a probe, we cloned the corresponding wild type allele (PTB1) of a mutated gene, which could completely complement the arsenate-resistance phenotype of AR3. The size of PTB1 cDNA is about 6.0kb and it encodes a putative protein comprising 1,666 amino acid residues. This protein exhibits significant sequence similarity with the yeast Pho89 protein, which is known to be a Na^+/Pi co-transporter, although the PTB1 protein carries an additional Gln-and Gly-rich large hydrophilic region in the middle of its primary structure. Analyses of arsenic accumulation and release revealed that PTB1-disrupted cells show arsenate resistance due to low arsenate uptake. These results suggest that the PTB1 protein is a factor involved in arsenate (or, Pi) uptake. Kinetics of Pi uptake revealed that the activity of high-affinity Pi transport component in AR3 is more activated than that in the wild type.
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