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A CDC25 homologue from rice functions as an arsenate reductase

A CDC25 homologue from rice functions as an arsenate reductase • Enzymatic reduction of arsenate to arsenite is the first step in arsenate metabolism in all organisms studied. The rice genome contains two ACR2‐like genes, OsACR2.1 and OsACR2.2, which may be involved in regulating arsenic metabolism in rice. • Here, we cloned both OsACR2 genes and expressed them in an Escherichia coli strain in which the arsC gene was deleted and in a yeast (Saccharomyces cerevisiae) strain with a disrupted ACR2 gene. OsACR2.1 complemented the arsenate hypersensitive phenotype of E. coli and yeast. OsACR2.2 showed much less ability to complement. • The gene products were purified and demonstrated to reduce arsenate to arsenite in vitro, and both exhibited phosphatase activity. In agreement with the complementation results, OsACR2.1 exhibited higher reductase activity than OsACR2.2. Mutagenesis of cysteine residues in the putative active site HC(X)5R motif led to nearly complete loss of both phosphatase and arsenate reductase activities. •  In planta expression of OsACR2.1 increased dramatically after exposure to arsenate. OsACR2.2 was observed only in roots following arsenate exposure, and its expression was less than OsACR2.1. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png New Phytologist Wiley

A CDC25 homologue from rice functions as an arsenate reductase

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References (46)

Publisher
Wiley
Copyright
Copyright © 2007 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0028-646X
eISSN
1469-8137
DOI
10.1111/j.1469-8137.2007.02009.x
pmid
17388894
Publisher site
See Article on Publisher Site

Abstract

• Enzymatic reduction of arsenate to arsenite is the first step in arsenate metabolism in all organisms studied. The rice genome contains two ACR2‐like genes, OsACR2.1 and OsACR2.2, which may be involved in regulating arsenic metabolism in rice. • Here, we cloned both OsACR2 genes and expressed them in an Escherichia coli strain in which the arsC gene was deleted and in a yeast (Saccharomyces cerevisiae) strain with a disrupted ACR2 gene. OsACR2.1 complemented the arsenate hypersensitive phenotype of E. coli and yeast. OsACR2.2 showed much less ability to complement. • The gene products were purified and demonstrated to reduce arsenate to arsenite in vitro, and both exhibited phosphatase activity. In agreement with the complementation results, OsACR2.1 exhibited higher reductase activity than OsACR2.2. Mutagenesis of cysteine residues in the putative active site HC(X)5R motif led to nearly complete loss of both phosphatase and arsenate reductase activities. •  In planta expression of OsACR2.1 increased dramatically after exposure to arsenate. OsACR2.2 was observed only in roots following arsenate exposure, and its expression was less than OsACR2.1.

Journal

New Phytologist – Wiley

Published: Apr 1, 2007

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