Glutathione-mediated detoxification systems in plants

Dixon, David P.; Cummins, Ian; Cole, David J.; Edwards, Robert

doi:10.1016/s1369-5266(98)80114-3

Cited by 346 publications

(235 citation statements)

References 95 publications

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“…This activity was widely exhibited in the Arabidopsis GSTUs, with 25 of the 28 class members leading to the aberrant accumulation of S-acylated glutathione derivatives of fatty acids when expressed in E. coli. Short-chain glutathione thioesters derived from the detoxification of formaldehyde (25) and methylglyoxal (26) are well known metabolites in both eukaryotes and prokaryotes. However, the long chain thioesters observed after the expression of the GSTUs in bacteria have not to our knowledge been identified as metabolites in vivo, although they have been chemically synthesized from acyl chlorides (13) and by transacylation from the respective CoA derivatives (27).…”

Section: Discussionmentioning

confidence: 99%

Selective Binding of Glutathione Conjugates of Fatty Acid Derivatives by Plant Glutathione Transferases

Dixon

Edwards

2009

Journal of Biological Chemistry

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Proteomic studies with Arabidopsis thaliana have revealed that the plant-specific Tau (U) class glutathione transferases (GSTs) are selectively retained by S-hexylglutathione affinity supports. Overexpression of members of the Arabidopsis GST superfamily in Escherichia coli showed that 25 of the complement of 28 GSTUs caused the aberrant accumulation of acylated glutathione thioesters in vivo, a perturbation that was not observed with other GST classes. Each GSTU caused a specific group of fatty acyl derivatives to accumulate, which varied in chain length (C 6 to C 18 ), additional oxygen content (0 or 1), and desaturation (0 or 1). Thioesters bound tightly to recombinant GSTs (K d ϳ 1 M), explaining their accumulation. Transient expression of GSTUs in Nicotiana benthamiana followed by recovery by Strep-tag affinity chromatography allowed the respective plant ligands to be extracted and characterized. Again, each GST showed a distinct profile of recovered metabolites, notably glutathionylated oxophytodienoic acid and related oxygenated fatty acids. Similarly, the expression of the major Tau protein GSTU19 in the endogenous host Arabidopsis led to the selective binding of the glutathionylated oxophytodienoic acid-glutathione conjugate, with the enzyme able to catalyze the conjugation reaction. Additional ligands identified in planta included other fatty acid derivatives including divinyl ethers and glutathionylated chlorogenic acid. The strong and specific retention of various oxygenated fatty acids by each GSTU and the conservation in binding observed in the different hosts suggest that these proteins have selective roles in binding and conjugating these unstable metabolites in vivo.In plants, the glutathione transferases (GSTs 2 ; EC 2.5.1.18) are a superfamily of proteins with the dominant Phi (F) and Tau (U) classes having largely undefined functions in endogenous metabolism (1). This is in contrast to their relatively well studied role in catalyzing the glutathione conjugation of herbicides (2). Because of their importance in determining herbicide selectivity, these proteins have been purified from a range of major crops including maize (3), soybean (4), and wheat (5, 6). One approach which has been commonly applied to isolate these proteins is affinity chromatography using a range of glutathione (GSH) derivatives as ligands (7). These ligands often display a surprising degree of selectivity in capturing specific GSTs. Thus, in wheat extracts, whereas GSH-agarose effectively isolated GSTFs, S-hexylglutathione (GS-hexyl) proved to be a selective ligand for GSTUs (5). Similarly, glutathionylated dyes have proved to be highly selective for specific GSTs in maize (8).In each application, the use of GSH derivatives as affinity ligands has been developed through serendipity, with limited attention directed to the potential significance of such binding selectivity in relating to the nature of in vivo substrates and reaction products. At a molecular level, crystallographic studies with both plant GSTFs (9) and GSTUs...

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Section: Discussionmentioning

confidence: 99%

Selective Binding of Glutathione Conjugates of Fatty Acid Derivatives by Plant Glutathione Transferases

Dixon

Edwards

2009

Journal of Biological Chemistry

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“…Together, these findings indicate that the enhanced TNT tolerance observed in the overexpressing lines is due to direct glutathionylation of TNT rather than enhanced GPOX activity. Chemical treatments associated with the production of active oxygen species have been shown to cause a strong up-regulation of GPOX activity (Dixon et al, 1998;Dixon and Edwards, 2010). In bacteria, TNT can undergo one-electron reduction to produce a nitroanion radical, which reacts with oxygen to form a superoxide radical, with the regeneration of TNT.…”

Section: Glutathione-tnt Productsmentioning

confidence: 99%

“…The overexpression of plant GSTs has been shown to increase resistance to a range of stresses, with some t class GSTs shown to detoxify herbicides via a conjugation activity (Dixon and Edwards, 2010;Cummins et al, 2011). Many Arabidopsis GSTs (in common with some mammalian and other plant GSTs) exhibit a glutathione-dependent peroxide (GPOX) activity (Dixon and Edwards, 2010), catalyzing the reduction of lipid hydroperoxides to the respective monohydroxyalcohols, an activity that confers tolerance to a number of oxidative stresses (Dixon et al, 1998;Dixon and Edwards, 2010). Here, we expressed, purified, and characterized TNT-responsive Arabidopsis GSTs and investigated their contribution toward the detoxification of TNT in Arabidopsis.…”

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confidence: 99%

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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The explosive 2,4,6-trinitrotoluene (TNT) is a major worldwide military pollutant. The presence of this toxic and highly persistent pollutant, particularly at military sites and former manufacturing facilities, presents various health and environmental concerns. Due to the chemically resistant structure of TNT, it has proven to be highly recalcitrant to biodegradation in the environment. Here, we demonstrate the importance of two glutathione transferases (GSTs), GST-U24 and GST-U25, from Arabidopsis (Arabidopsis thaliana) that are specifically up-regulated in response to TNT exposure. To assess the role of GST-U24 and GST-U25, we purified and characterized recombinant forms of both enzymes and demonstrated the formation of three TNT glutathionyl products. Importantly, GST-U25 catalyzed the denitration of TNT to form 2-glutathionyl-4,6-dinitrotoluene, a product that is likely to be more amenable to subsequent biodegradation in the environment. Despite the presence of this biochemical detoxification pathway in plants, physiological concentrations of GST-U24 and GST-U25 result in only a limited innate ability to cope with the levels of TNT found at contaminated sites. We demonstrate that Arabidopsis plants overexpressing GST-U24 and GST-U25 exhibit significantly enhanced ability to withstand and detoxify TNT, properties that could be applied for in planta detoxification of TNT in the field. The overexpressing lines removed significantly more TNT from soil and exhibited a corresponding reduction in glutathione levels when compared with wild-type plants. However, in the absence of TNT, overexpression of these GSTs reduces root and shoot biomass, and although glutathione levels are not affected, this effect has implications for xenobiotic detoxification.The containment and cleanup of environmental pollutants is increasingly both a legal requirement and a responsible action in many developed countries. The most commonly used explosives in military weapons are 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and their continual use, along with production and decommissioning, are progressively contaminating millions of hectares of military land . Bioremediation of TNT is particularly challenging, as the electron-withdrawing properties of the three nitro groups render the aromatic ring particularly resistant to oxidative attack and ring cleavage by microbial oxygenases, which in the environment are normally central to the biodegradation of aromatic compounds (Qasim et al., 2007). In the United States, the Environmental Protection Agency and the military are addressing methods by which toxic TNT and RDX can be contained and detoxified on active military training ranges. One way this problem might be tackled is through the use of plants that are adapted to detoxify these compounds. This could be achieved either by traditional breeding programs or by genetic modification, as has been demonstrated previously for both RDX and TNT (Hannink et al., 2001;Rylott et al., 2006;Jackson et al., 2007).In t...

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“…Peroxidases are a collection of enzymes that catalyse the breakdown of H 2 O 2 (Mittler 1993), preventing cellular peroxidation and other possible damages. Reduction of glutathione by GPX decreases H 2 O 2 activity (Dixon 1998), especially under stress. Therefore, the collection of antioxidants can help the plant handle the stress.…”

Section: Introductionmentioning

confidence: 97%

The effects of selenium and other micronutrients on the antioxidant activities and yield of corn (Zea mays L.) under drought stress

Sajedi

Ardakani

Madani

et al. 2011

Physiol Mol Biol Plants

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The effects of selenium (Se) on plant growth under drought stress and in the presence of micronutrients are yet to be investigated. Hence, in a field experiment in 2007 the effects of Se and micronutrients including iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B) and molybdenum (Mo) were evaluated on corn (Zea mays L.) grain yield under drought stress. Main-and sub-plots were devoted to irrigation (control and water stressed at the eight-leaf, blister and grain filling stages) and micronutrients treatments, respectively. Micronutrients were foliarly applied at 2 l ha -1 at the six-leaf stage, one week before tasseling, using a corn fertilizer, called biomin containing (on the basis of dry weight percentage) Fe (2.6), Zn (4

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Glutathione-mediated detoxification systems in plants

Cited by 346 publications

References 95 publications

Selective Binding of Glutathione Conjugates of Fatty Acid Derivatives by Plant Glutathione Transferases

Selective Binding of Glutathione Conjugates of Fatty Acid Derivatives by Plant Glutathione Transferases

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

The effects of selenium and other micronutrients on the antioxidant activities and yield of corn (Zea mays L.) under drought stress

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