Dissection of glutathione conjugate turnover in yeast

Wünschmann, Jana; Krajewski, Matthias; Letzel, Thomas; Huber, E.M.; Ehrmann, Alexander; Grill, Erwin; Lendzian, Klaus J.

doi:10.1016/j.phytochem.2009.09.034

Cited by 29 publications

(27 citation statements)

References 53 publications

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“…According to recent publications (40,41), ␥-GT plays a critical role in the detoxification of monochlorobimane. This electrophilic xenobiotic is first conjugated to GSH, giving glutathione S-bimane.…”

Section: Discussionmentioning

confidence: 99%

“…This electrophilic xenobiotic is first conjugated to GSH, giving glutathione S-bimane. Glutathione S-bimane is then catabolized to Cys-bimane through two pathways, both requiring ␥-GT for the cleavage of a ␥-bond (cleavage of glutathione S-bimane into Cys-Gly-bimane and cleavage of ␥-Glu-Cys-bimane) (41). This suggests that the physiological substrates of the ␥-GT are the GSH conjugates.…”

Section: Discussionmentioning

confidence: 99%

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Glutathione Degradation Is a Key Determinant of Glutathione Homeostasis

Baudouin‐Cornu

Lagniel

Kumar

et al. 2012

Journal of Biological Chemistry

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Background: Intracellular concentration of glutathione, an essential sulfur compound, is tightly controlled. Results: In yeast, glutathione degradation is faster than previously published, and glutathione intracellular concentration does not affect its synthesis. Conclusion: Glutathione degradation is a key determinant of glutathione homeostasis. Significance: This work challenges notions on glutathione synthesis and degradation, which were considered as established.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Glutathione Degradation Is a Key Determinant of Glutathione Homeostasis

Baudouin‐Cornu

Lagniel

Kumar

et al. 2012

Journal of Biological Chemistry

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“…In yeast, the g-glutamyl transpeptidase activity is required for extracellular secretion of GS conjugates, releasing CysGly-and Cys-bimane into the culture medium (Wü nschmann et al, 2010). The secreted Cys conjugates might reenter the cell.…”

Section: Discussionmentioning

confidence: 99%

“…1) has not been unequivocally identified in plants. In yeast, the first degradation step is mediated by a single GGT, which is also required for extracellular secretion of Cys conjugates (Wü nschmann et al, 2010). Plants possibly recruit the GGTs in a similar manner or, alternatively, g-glutamyl cyclotransferase and 5-oxoprolinase, which can convert the glutamyl moiety of g-glutamylcysteinyl (g-GluCys) into Glu (Ohkama-Ohtsu et al, 2008).…”

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confidence: 99%

Cytosolic Action of Phytochelatin Synthase

et al. 2010

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Glutathionylation of compounds is an important reaction in the detoxification of electrophilic xenobiotics and in the biosynthesis of endogenous molecules. The glutathione conjugates (GS conjugates) are further processed by peptidic cleavage reactions. In animals and plants, g-glutamyl transpeptidases initiate the turnover by removal of the glutamate residue from the conjugate. Plants have a second route leading to the formation of g-glutamylcysteinyl (g-GluCys) conjugates. Phytochelatin synthase (PCS) is well known to mediate the synthesis of heavy metal-binding phytochelatins. In addition, the enzyme is also able to catabolize GS conjugates to the g-GluCys derivative. In this study, we addressed the cellular compartmentalization of PCS and its role in the plant-specific g-GluCys conjugate pathway in Arabidopsis (Arabidopsis thaliana). Localization studies of both Arabidopsis PCS revealed a ubiquitous presence of AtPCS1 in Arabidopsis seedlings, while AtPCS2 was only detected in the root tip. A functional AtPCS1:eGFP (enhanced green fluorescent protein) fusion protein was localized to the cytosolic compartment. Inhibition of the vacuolar import of GS-bimane conjugate via azide treatment resulted in both a strong accumulation of g-GluCys-bimane and a massive increase of the cellular cysteine to GS-bimane ratio, which was not observed in PCS-deficient lines. These findings support a cytosolic action of PCS. Analysis of a triple mutant deficient in both Arabidopsis PCS and vacuolar g-glutamyl transpeptidase GGT4 is consistent with earlier observations of an efficient sequestration of GS conjugates into the vacuole and the requirement of GGT4 for their turnover. Hence, PCS contributes specifically to the cytosolic turnover of GS conjugates, and AtPCS1 plays the prominent role. We discuss a potential function of PCS in the cytosolic turnover of GS conjugates.

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“…In mammalian cells, catabolism of glutathione-S-conjugates is initiated by the removal of the N-terminal Glu residue catalyzed by g-glutamyl transpeptidase, which is the rate-limiting step (Meister, 1995). Two modes of glutathione-S-conjugates catabolism have been proposed in plants (Wü nschmann et al, 2010). One mode is that the initial step is the removal of the Glu residue from the N terminus catalyzed by g-glutamyl transpeptidases, for example, GGTs in Arabidopsis (Ohkama-Ohtsu et al, 2007a, 2007b.…”

Section: Both Mkk9 Activation and B Cinerea Infection Led To Accumulmentioning

confidence: 99%

Glutathione-Indole-3-Acetonitrile Is Required for Camalexin Biosynthesis in Arabidopsis thaliana

et al. 2011

The Plant Cell

115

119

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Camalexin, a major phytoalexin in Arabidopsis thaliana, consists of an indole ring and a thiazole ring. The indole ring is produced from Trp, which is converted to indole-3-acetonitrile (IAN) by CYP79B2/CYP79B3 and CYP71A13. Conversion of Cys(IAN) to dihydrocamalexic acid and subsequently to camalexin is catalyzed by CYP71B15. Recent studies proposed that Cys derivative, not Cys itself, is the precursor of the thiazole ring that conjugates with IAN. The nature of the Cys derivative and how it conjugates to IAN and subsequently forms Cys(IAN) remain obscure. We found that protein accumulation of multiple glutathione S-transferases (GSTs), elevation of GST activity, and consumption of glutathione (GSH) coincided with camalexin production. GSTF6 overexpression increased and GSTF6-knockout reduced camalexin production. Arabidopsis GSTF6 expressed in yeast cells catalyzed GSH(IAN) formation. GSH(IAN), (IAN)CysGly, and gGluCys(IAN) were determined to be intermediates within the camalexin biosynthetic pathway. Inhibitor treatments and mutant analyses revealed the involvement of g-glutamyl transpeptidases (GGTs) and phytochelatin synthase (PCS) in the catabolism of GSH(IAN). The expression of GSTF6, GGT1, GGT2, and PCS1 was coordinately upregulated during camalexin biosynthesis. These results suggest that GSH is the Cys derivative used during camalexin biosynthesis, that the conjugation of GSH with IAN is catalyzed by GSTF6, and that GGTs and PCS are involved in camalexin biosynthesis.

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Dissection of glutathione conjugate turnover in yeast

Cited by 29 publications

References 53 publications

Glutathione Degradation Is a Key Determinant of Glutathione Homeostasis

Glutathione Degradation Is a Key Determinant of Glutathione Homeostasis

Cytosolic Action of Phytochelatin Synthase

Glutathione-Indole-3-Acetonitrile Is Required for Camalexin Biosynthesis in Arabidopsis thaliana

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