Isolation and characterization of an auxin-inducible glutathione S-transferase gene of Arabidopsis thaliana

Kop, D.A.M. van der; Schuyer, Monique; Scheres, Ben; Zaal, Bert J. van der; Hooykaas, Paul J. J.

doi:10.1007/bf00019016

Cited by 32 publications

(16 citation statements)

References 20 publications

(27 reference statements)

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“…In Arabidopsis, the safener dichlormid was only effective in inducing gstl1, suggesting that this safener, which is used to increase tolerance to chloroacetanilide herbicides in maize by enhancing the expression of multiple Phi and Tau GSTs (45), was far less active as a safener in Arabidopsis. The induction of gstl1 was not seen with the GST substrates CDNB and fluorodifen; instead these compounds were most effective in inducing the Tau GST gstu1, a gene shown previously (46) to be regulated by auxin. This result suggested that GST induction by safeners and xenobiotic substrates of GSTs must proceed by distinct recognition/signaling pathways.…”

Section: Discussionmentioning

confidence: 63%

Functional Divergence in the Glutathione Transferase Superfamily in Plants

Dixon

Davis

Edwards

2002

Journal of Biological Chemistry

371

161

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Searches with the human Omega glutathione transferase (GST) identified two outlying groups of the GST superfamily in Arabidopsis thaliana which differed from all other plant GSTs by containing a cysteine in place of a serine at the active site. One group consisted of four genes, three of which encoded active glutathionedependent dehydroascorbate reductases (DHARs). Two DHARs were predicted to be cytosolic, whereas the other contained a chloroplast targeting peptide. The DHARs were also active as thiol transferases but had no glutathione conjugating activity. Unlike most other GSTs, DHARs were monomeric. The other class of GST comprised two genes termed the Lambda GSTs (GSTLs). The recombinant GSTLs were also monomeric and had glutathione-dependent thiol transferase activity. One GSTL was cytosolic, whereas the other was chloroplasttargeted. When incubated with oxidized glutathione, the putative active site cysteine of the GSTLs and cytosolic DHARs formed mixed disulfides with glutathione, whereas the plastidic DHAR formed an intramolecular disulfide. DHAR S-glutathionylation was consistent with a proposed catalytic mechanism for dehydroascorbate reduction. Roles for the cytosolic DHARs and GSTLs as antioxidant enzymes were also inferred from the induction of the respective genes following exposure to chemicals and oxidative stress.

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Section: Discussionmentioning

confidence: 63%

Functional Divergence in the Glutathione Transferase Superfamily in Plants

Dixon

Davis

Edwards

2002

Journal of Biological Chemistry

371

161

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“…The AtGSTU19 protein has significant similarity with other Arabidopsis tau class GSTs encoded by genes located outside the cluster on chromosome one (Table III), notably AtGSTU5 (GenBank accession no. D44465), which has been characterized previously (Van der Kop et al, 1996). AtGSTU19 is also very similar to members of the maize tau class of safener-inducible GSTs, ZmGSTU1 and ZmGSTU2 Figure 1.…”

Section: Table II Effect Of Safeners On Total Glutathione Content Inmentioning

confidence: 66%

Induction of Glutathione S-Transferases in Arabidopsis by Herbicide Safeners

et al. 2002

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Herbicide safeners increase herbicide tolerance in cereals but not in dicotyledenous crops. The reason(s) for this difference in safening is unknown. However, safener-induced protection in cereals is associated with increased expression of herbicide detoxifying enzymes, including glutathione S-transferases (GSTs). Treatment of Arabidopsis seedlings growing in liquid medium with various safeners similarly resulted in enhanced GST activities toward a range of xenobiotics with benoxacor, fenclorim, and fluxofenim being the most effective. Safeners also increased the tripeptide glutathione content of Arabidopsis seedlings. However, treatment of Arabidopsis plants with safeners had no effect on the tolerance of seedlings to chloroacetanilide herbicides. Each safener produced a distinct profile of enhanced GST activity toward different substrates suggesting a differential induction of distinct isoenzymes. This was confirmed by analysis of affinity-purified GST subunits by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. AtGSTU19, a tau class GST, was identified as a dominant polypeptide in all samples. When AtGSTU19 was expressed in Escherichia coli, the recombinant enzyme was highly active toward 1-chloro-2,4-dinitrobenzene, as well as chloroacetanilide herbicides. Immunoblot analysis confirmed that AtGSTU19 was induced in response to several safeners. Differential induction of tau GSTs, as well as members of the phi and theta classes by safeners, was demonstrated by RNA-blot analysis. These results indicate that, although Arabidopsis may not be protected from herbicide injury by safeners, at least one component of their detoxification systems is responsive to these compounds.Plants actively detoxify both endogenous toxins, such as secondary metabolites and degradation products arising from oxidative stress, and exogenous man-made chemicals, such as herbicides, using a three-phase detoxification system (Neuefeind et al., 1997). In the first phase, oxidation, reduction, or hydrolysis reactions catalyzed by enzymes such as cytochrome P450 monooxygenases result in the exposure, or introduction, of a functional group. Phase two enzymes then catalyze the conjugation of these metabolites with sugars or the tripeptide glutathione (GSH). In the case of GSH, glutathione S-transferases (GSTs) catalyze this conjugation reaction. In the third phase of metabolism, molecules "tagged" with GSH are recognized by ATP-binding cassette transporters in the tonoplast or plasma membrane, which then transfer these conjugates into the vacuole or apoplast (Rea, 1999).GSTs constitute a family of multifunctional enzymes present in both plants and animals. These dimeric enzymes catalyze the conjugation of GSH to a variety of electrophilic, hydrophobic, and often toxic substrates, thereby reducing their toxicity (Marrs, 1996;Dixon et al., 1998). In addition to GSH conjugation, GSTs may also exhibit glutathione peroxidase (GPOX) or isomerase activities, or function as binding proteins known as ligandins (Edwards et al., ...

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“…Exposure to H 2 O 2 , diamide, 2,4-D, salicylic acid, and methyl viologen did not increase the levels of gsh1, gsh2, or gr1 mRNA, as shown in Figure 3. They did, however, increase the level of mRNA for a GST, parA, which is known to be activated by multiple stimuli (van der Kop et al, 1996). JA, unlike the other compounds tested, increased the level of all three mRNAs involved in GSH metabolism.…”

Section: Coordinated Expression Of Gsh Metabolic Genes In Response To Jamentioning

confidence: 78%

Glutathione Metabolic Genes Coordinately Respond to Heavy Metals and Jasmonic Acid in Arabidopsis

1998

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Glutathione plays a pivotal role in protecting plants from environmental stresses, oxidative stress, xenobiotics, and some heavy metals. Arabidopsis plants treated with cadmium or copper responded by increasing transcription of the genes for glutathione synthesis, ␥ -glutamylcysteine synthetase and glutathione synthetase, as well as glutathione reductase. The response was specific for those metals whose toxicity is thought to be mitigated through phytochelatins, and other toxic and nontoxic metals did not alter mRNA levels. Feeding experiments suggested that neither oxidative stress, as results from exposure to H 2 O 2 , nor oxidized or reduced glutathione levels were responsible for activating transcription of these genes. Jasmonic acid also activated the same suite of genes, which suggests that it might be involved in the signal transduction pathway for copper and cadmium. Jasmonic acid treatment increased mRNA levels and the capacity for glutathione synthesis but did not alter the glutathione content in unstressed plants, which supports the idea that the glutathione concentration is controlled at multiple levels. INTRODUCTIONGlutathione (GSH), the tripeptide ␥ -glutamylcysteinylglycine, is the major source of non-protein thiols in most plant cells (Bergmann and Rennenberg, 1993). GSH plays a central role in protecting plants from environmental stresses, including oxidative stress due to the generation of active oxygen species, xenobiotics, and some heavy metals.GSH is involved in quenching reactive oxygen species (Larson, 1988; Alscher, 1989; Foyer et al., 1994b). The ascorbate/GSH cycle reduces H 2 O 2 to water (Foyer and Halliwell, 1976; Alscher, 1989). Ascorbate is also important in maintaining ␣ -tocopherol in the reduced state and therefore links GSH to the dominant free radical scavenger in membranes (Hess, 1994). Plants detoxify many organic contaminants by conjugating them or their metabolites to GSH for storage or further metabolism (Lamoureux et al., 1994). These reactions are catalyzed by glutathione S -transferases (GSTs). Plants are protected from some metals, with cadmium and copper being the most studied, by a group of ␥ -glutamylcysteine ( ␥ -EC) peptides, the phytochelatins (PCs). These molecules have the general structure ( ␥ -Glu-Cys) 2-11 -Gly. They are formed by the polymerization of GSH catalyzed by the transpeptidase phytochelatin synthase (Grill et al., 1985(Grill et al., , 1987 Chen et al., 1997). The PCs bind metals in the cytosol, and the PC metal complex is sequestered in the vacuole (Rauser, 1990).GSH is synthesized from glutamate, cysteine, and glycine by a two-step ATP-dependent reaction (Meister and Anderson, 1983). The first reaction forms ␥ -EC from glutamate and cysteine by the enzyme ␥ -EC synthetase (Hell and Bergmann, 1990), which is encoded by gsh1 (May and Leaver, 1995). GSH is then synthesized by the ligation of ␥ -EC and glycine in the reaction catalyzed by the enzyme GSH synthetase, which is encoded by gsh2 (Wang and Oliver, 1996). When GSH is oxidized as part of ...

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Isolation and characterization of an auxin-inducible glutathione S-transferase gene of Arabidopsis thaliana

Cited by 32 publications

References 20 publications

Functional Divergence in the Glutathione Transferase Superfamily in Plants

Functional Divergence in the Glutathione Transferase Superfamily in Plants

Induction of Glutathione S-Transferases in Arabidopsis by Herbicide Safeners

Glutathione Metabolic Genes Coordinately Respond to Heavy Metals and Jasmonic Acid in Arabidopsis

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