Journal Article

Insertional Mutagenesis in a Homologue of a Pi Transporter Gene Confers Arsenate Resistance on <i>Chlamydomonas</i>

Isao Kobayashi, Shoko Fujiwara, Kosuke Shimogawara, Toshikazu Kaise, Hideaki Usuda and Mikio Tsuzuki

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 44, issue 6, pages 597-606
Published in print June 2003 | ISSN: 0032-0781
Published online June 2003 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcg081
Insertional Mutagenesis in a Homologue of a Pi Transporter Gene Confers Arsenate Resistance on Chlamydomonas

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  • Biochemistry
  • Molecular and Cell Biology
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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 6.0 kb 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.

Keywords: Keywords: Arsenate resistance — Chlamydomonas reinhardtii — Pi transporter — Pi uptake.; Abbreviations: HXT, hexose transporter; PC, phytochelatin; RT-PCR, reverse transcriptional polymerase chain reaction; TAP medium, Tris-acetate-phosphate medium.

Journal Article.  6659 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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