Properties of the Arsenate Reductase of Plasmid R773

Gladysheva, Tatiana; Oden, Kristine L.; Rosen, Barry P.

doi:10.1021/bi00189a033

Cited by 189 publications

(168 citation statements)

References 19 publications

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“…We searched various plant databases for genes encoding amino acid sequence homologs of the previously described E. coli ArsC and yeast ScACR2 arsenate reductases (12)(13)(14). We found sequences that were the likely plant homologs of the ScAcr2 protein sequence, but nothing related in overall sequence to ArsC.…”

Section: Resultsmentioning

confidence: 99%

Hyperaccumulation of arsenic in the shoots of Arabidopsis silenced for arsenate reductase (ACR2)

Dhankher

Rosen

McKinney

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

238

144

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Endogenous plant arsenate reductase (ACR) activity converts arsenate to arsenite in roots, immobilizing arsenic below ground. By blocking this activity, we hoped to construct plants that would mobilize more arsenate aboveground. We have identified a single gene in the Arabidopsis thaliana genome, ACR2, with moderate sequence homology to yeast arsenate reductase. Expression of ACR2 cDNA in Escherichia coli complemented the arsenate-resistant and arsenate-sensitive phenotypes of various bacterial ars operon mutants. RNA interference reduced ACR2 protein expression in Arabidopsis to as low as 2% of wild-type levels. The various knockdown plant lines were more sensitive to high concentrations of arsenate, but not arsenite, than wild type. The knockdown lines accumulated 10-to 16-fold more arsenic in shoots (350 -500 ppm) and retained less arsenic in roots than wild type, when grown on arsenate medium with <8 ppm arsenic. Reducing expression of ACR2 homologs in tree, shrub, and grass species should play a vital role in the phytoremediation of environmental arsenic contamination.Escherichia coli ArsC ͉ drinking water ͉ CDC25 ͉ toxicant ͉ arsenic pollution E nvironmental arsenic pollution is widely recognized as a global health problem (1) (www.epa.gov͞ogwdw͞ars͞arsenic.html). High levels of arsenic in soil and drinking water have been reported around the world, but the situation is worst in India and Bangladesh, where Ͼ400 million people are at risk of arsenic poisoning (2). The World Health Organization predicts that long-term exposure to arsenic could reach epidemic proportions, estimating that 1 in 10 people in the most contaminated areas may ultimately die from diseases related to arsenic poisoning (3). The high financial cost associated with repairing the environmental damage by using physical remediation methods such as excavation and reburial make these technologies unacceptable for cleaning up the vast areas of the planet that need arsenic remediation. As a result, the overwhelming majority of arsenic-contaminated sites are not being cleaned up.Phytoremediation is the use of plants to clean up environmental pollutants and is considered an important alternative to physical methods for cleaning up arsenic (4). Our objective is to develop a genetics-based arsenic phytoremediation strategy that can be used in any plant species. Plants that hyperaccumulate arsenic to high levels aboveground would be harvested and the arsenic further concentrated by incineration. In previous studies, we engineered model plants expressing a bacterial arsenate reductase (ArsC; EC 1.20.4.1) aboveground and constitutively expressing ␥-glutamylcysteine synthetase (5). By reducing arsenate to arsenite in leaves and trapping arsenite in thiol-peptide complexes, these plants accumulate 3-fold more arsenic aboveground than wild type and are also highly tolerant to toxic levels of arsenic. The research described herein extends these observations and attacks a particular problem limiting the engineered phytoremediation of arsenic: its transpor...

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Section: Resultsmentioning

confidence: 99%

Hyperaccumulation of arsenic in the shoots of Arabidopsis silenced for arsenate reductase (ACR2)

Dhankher

Rosen

McKinney

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

238

144

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“…They are essential for the glutathione-dependent reduction of ribonucleotides by ribonucleotide reductase (Holmgren, 1976(Holmgren, , 1979Luthman et al, 1979;Luthman & Holmgren, 1982). They have also been shown to play a role in the reduction of sulfate (Russel et al, 1990;Tsang, 1981), arsenate (Gladysheva et al, 1994;Wells et al, 1990), and ascorbate (Ahn & Moss, 1992;Gravina & Mieyal, 1993). They preferentially reduce glutathione-containing mixed disul®des (Gravina & Mieyal, 1993;Jung & Thomsa, 1996) due to the glutathione binding site present on the protein (Bushweller et al, 1994) .…”

Section: Introductionmentioning

confidence: 99%

The NMR solution structure of human glutaredoxin in the fully reduced form

Sun

Berardi

Bushweller

1998

Journal of Molecular Biology

100

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The determination of the nuclear magnetic resonance (NMR) solution structure of fully reduced human glutaredoxin is described. A total of 1159 useful nuclear Overhauser effect (NOE) upper distance constraints and 187 dihedral angle constraints were obtained as the input for the structure calculations for which the torsion angle dynamics program DYANA has been utilized followed by energy minimization in water with the AMBER force ®eld as implemented in the program OPAL. The resulting 20 conformers have an average root-mean-square deviation value relative to the mean coordinates of 0.54 A Ê for all the backbone atoms N, C a and C H , and of 1.01 A Ê for all heavy atoms. Human glutaredoxin consists of a four-stranded mixed b-sheet composed of residues 15 to 19, 43 to 47, 72 to 75 and 78 to 81, and ®ve a-helices composed of residues 4 to 9, 24 to 34, 54 to 65, 83 to 91, and 94 to 100. Comparisons with the structures of Escherichia coli glutaredoxin-1, pig liver glutaredoxin and human thioredoxin were made. Electrostatic calculations on the human glutaredoxin structure and that of related proteins provide an understanding of the variation of pK a values for the nucleophilic cysteine in the active site observed among these proteins. In addition, the high-resolution NMR solution structure of human glutaredoxin has been used to model the binding site for glutathione and for ribonucleotide reductase B1 by molecular dynamics simulations.

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“…Pentavalent arsenic is transported into cells via phosphate transport systems in both prokaryotes (5) and eukaryotes (6). It is reduced to the more toxic trivalent arsenite by arsenate reductases (7)(8)(9). Arsenite can be detoxified either by extrusion from cells or by sequestration within intracellular organelles as thiol conjugates (3,4,10).…”

mentioning

confidence: 99%

Arsenite transport by mammalian aquaglyceroporins AQP7 and AQP9

Liu

Shen

Carbrey

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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460

298

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Much is known about the transport of arsenite and antimonite into microbes, but the identities of mammalian transport proteins are unknown. The Saccharomyces cerevisiae FPS1 gene encodes a membrane protein homologous to the bacterial aquaglyceroporin GlpF and to mammalian aquaglyceroporins AQP7 and AQP9. Fps1p mediates glycerol uptake and glycerol efflux in response to hypoosmotic shock. Fps1p has been shown to facilitate uptake of the metalloids arsenite and antimonite, and the Escherichia coli homolog, GlpF, facilitates the uptake and sensitivity to metalloid salts. In this study, the ability of mammalian aquaglyceroporins AQP7 and AQP9 to substitute for the yeast Fps1p was examined. The fps1⌬ strain of S. cerevisiae exhibits increased tolerance to arsenite and antimonite compared to a wild-type strain. Introduction of a plasmid containing AQP9 reverses the metalloid tolerance of the deletion strain. AQP7 was not expressed in yeast. The fps1⌬ cells exhibit reduced transport of 73 As(III) or 125 Sb(III), but uptake is enhanced by expression of AQP9. Xenopus laevis oocytes microinjected with either AQP7 or AQP9 cRNA exhibited increased transport of 73 As(III). These results suggest that AQP9 and AQP7 may be a major routes of arsenite uptake into mammalian cells, an observation potentially of large importance for understanding the action of arsenite as a human toxin and carcinogen, as well as its efficacy as a chemotherapeutic agent for acute promyelocytic leukemia.Fps1p ͉ GlpF ͉ acute promyelocytic leukemia

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Properties of the Arsenate Reductase of Plasmid R773

Cited by 189 publications

References 19 publications

Hyperaccumulation of arsenic in the shoots of Arabidopsis silenced for arsenate reductase (ACR2)

Hyperaccumulation of arsenic in the shoots of Arabidopsis silenced for arsenate reductase (ACR2)

The NMR solution structure of human glutaredoxin in the fully reduced form

Arsenite transport by mammalian aquaglyceroporins AQP7 and AQP9

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