Differential Regulation of Serine Acetyltransferase Is Involved in Nickel Hyperaccumulation in Thlaspi goesingense

Na, GunNam; Salt, David E.

doi:10.1074/jbc.m111.247411

Cited by 19 publications

(10 citation statements)

References 43 publications

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“…Both species were grown from seeds collected from plants growing on contaminated sites where S input from industry (Jena) and smelting activities (Vogel-Mikus et al, 2005) probably was high. Unexpected, and in contrast to our working hypothesis, was the finding that N. caerulescens had the lowest GSH concentrations among the species  2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.plant-soil.com (Na and Salt, 2011a). This distinctive pattern was not followed by the species in this study with high GSH concentrations in T. arvense (nonhyperaccumulator) and N. praecox (hyperaccumulator) and lower concentrations in N. caerulescens (hyperaccumulator).…”

Section: Discussioncontrasting

confidence: 82%

“…It was hypothesized that in this Ni hyperaccumulator SA inhibits PC formation and activates serine-acetyl transferase (SAT) leading to accumulation of GSH and activation of glutathione reductase, thus protecting plants from Ni-induced oxidative stress (Freeman et al, 2005). These SAT isoforms are insensitive to inhibition by cystein (Na and Salt, 2011a). However, the observation that the inhibition of c-glutamylcysteine synthetase by L-buthionine sulfoximine (BSO) does not decrease metal hypertolerance in N. caerulescens (Schat et al, 2002) has been used as an argument against a role for GSH and PCs in metal tolerance in this hyperaccumulator (Krämer, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Cadmium‐induced changes in glutathione and phenolics of Thlaspi and Noccaea species differing in Cd accumulation

Llugany

Tolrà

Martin

et al. 2013

Z. Pflanzenernähr. Bodenk.

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Glutathione (GSH) and phenolics play an important role in plant defense against metal-ion toxicity. The antioxidant activity and metal-binding capacity of these compounds can account for the protective effects. In contrast to animal-cell models, however, the possible interplay among these substances in stress defense of plants is poorly investigated. This study compares the influence of cadmium (Cd) on the profiles of both soluble phenolics and GSH in shoots of different Thlaspi and Noccaea species: two ecotypes of the nonhyperaccumulator T. arvense differing in Cd resistance (ecotype Aigues Vives, Cd-sensitive, and ecotype Jena, Cd-resistant) and two Cd-tolerant Cd-Zn hyperaccumulators N. praecox and N. caerulescens (formerly Thlaspi praecox and T. caerulescens). To reveal the possible influence of Cd-induced sulfur (S) shortage on the stress response, plants receiving normal S concentrations (500 lM MgSO 4 ) and plants treated with surplus S (500 lM MgSO 4 + 500 lM K 2 SO 4 ) were analyzed. Our working hypothesis was that species differences in tolerance to high tissue Cd concentrations should be reflected by differences in endogenous levels of GSH and phenolic compounds. The results reveal clear species-dependent differences in both the constitutive patterns and the Cd-and S-induced changes in shoot concentrations of GSH and phenolics. However, no simple relationship between these shoot concentrations and Cd accumulation and tolerance can be established.

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Section: Discussioncontrasting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Cadmium‐induced changes in glutathione and phenolics of Thlaspi and Noccaea species differing in Cd accumulation

Llugany

Tolrà

Martin

et al. 2013

Z. Pflanzenernähr. Bodenk.

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“…In EhSAT3, the position equivalent to Met201 is already occupied by valine, which may account for its lack of sensitivity for cysteine inhibition. There are several studies indicating the importance of the C-terminal residues in Cys feedback inhibition [24], [25]. The Saito and his coworkers showed that Met to Ile mutation at the C-terminal 280 residue in the watermelon SAT decreased the Cys inhibition by 25 folds and Gly 277 Cys mutant also showed similar Cys inhibition [24].…”

Section: Discussionmentioning

confidence: 99%

“…In both EhSAT1 and EhSAT3, the equivalent residue of 280 is already Ile and 277 is Ile and Glu respectively (Figure S4), therefore we expect these residues may not play any role in Cys inhibition in Entamoeba SAT’s. By comparing A. thaliana and T. goesingense SAT sequences, GunNan and Salt [25] proposed that Pro and Ala at 268 and 270 th position of T. goesingense SAT might be responsible for Cys insensitivity. At these positions EhSAT1 has serine and glutanmine, while EhSAT3 has glutamine at both positions; moreover this C-terminal end region has very little sequence similarity between EhSAT’s and TgSAT (Figure S4).…”

Section: Discussionmentioning

confidence: 99%

Single Residue Mutation in Active Site of Serine Acetyltransferase Isoform 3 from Entamoeba histolytica Assists in Partial Regaining of Feedback Inhibition by Cysteine

et al. 2013

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The cysteine biosynthetic pathway is essential for survival of the protist pathogen Entamoeba histolytica, and functions by producing cysteine for countering oxidative attack during infection in human hosts. Serine acetyltransferase (SAT) and O-acetylserine sulfhydrylase (OASS) are involved in cysteine biosynthesis and are present in three isoforms each. While EhSAT1 and EhSAT2 are feedback inhibited by end product cysteine, EhSAT3 is nearly insensitive to such inhibition. The active site residues of EhSAT1 and of EhSAT3 are identical except for position 208, which is a histidine residue in EhSAT1 and a serine residue in EhSAT3. A combination of comparative modeling, multiple molecular dynamics simulations and free energy calculation studies showed a difference in binding energies of native EhSAT3 and of a S208H-EhSAT3 mutant for cysteine. Mutants have also been generated in vitro, replacing serine with histidine at position 208 in EhSAT3 and replacing histidine 208 with serine in EhSAT1. These mutants showed decreased affinity for substrate serine, as indicated by Km, compared to the native enzymes. Inhibition kinetics in the presence of physiological concentrations of serine show that IC50 of EhSAT1 increases by about 18 folds from 9.59 µM for native to 169.88 µM for H208S-EhSAT1 mutant. Similar measurements with EhSAT3 confirm it to be insensitive to cysteine inhibition while its mutant (S208H-EhSAT3) shows a gain of cysteine inhibition by 36% and the IC50 of 3.5 mM. Histidine 208 appears to be one of the important residues that distinguish the serine substrate from the cysteine inhibitor.

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“…Protein was quantified by Bradford method and NanoDrop ND-1000 (Thermo Scientific). Equal amounts of eluates were fractionated by SDS/PAGE and visualized by silver staining (Pierce) and Western blot by using a polyclonal anti-SAT antibody (44).…”

Section: Methodsmentioning

confidence: 99%

Cyclophilin 20-3 relays a 12-oxo-phytodienoic acid signal during stress responsive regulation of cellular redox homeostasis

Park

Viehhauser

et al. 2013

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

198

215

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The jasmonate family of phytohormones plays central roles in plant development and stress acclimation. However, the architecture of their signaling circuits remains largely unknown. Here we describe a jasmonate family binding protein, cyclophilin 20-3 (CYP20-3), which regulates stress-responsive cellular redox homeostasis. (+)-12-oxo-phytodienoic acid (OPDA) binding promotes CYP20-3 to form a complex with serine acetyltransferase 1, which triggers the formation of a hetero-oligomeric cysteine synthase complex with O -acetylserine(thiol)lyase B in chloroplasts. The cysteine synthase complex formation then activates sulfur assimilation that leads to increased levels of thiol metabolites and the buildup of cellular reduction potential. The enhanced redox capacity in turn coordinates the expression of a subset of OPDA-responsive genes. Thus, we conclude that CYP20-3 is a key effector protein that links OPDA signaling to amino acid biosynthesis and cellular redox homeostasis in stress responses.

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Differential Regulation of Serine Acetyltransferase Is Involved in Nickel Hyperaccumulation in Thlaspi goesingense

Cited by 19 publications

References 43 publications

Cadmium‐induced changes in glutathione and phenolics of Thlaspi and Noccaea species differing in Cd accumulation

Cadmium‐induced changes in glutathione and phenolics of Thlaspi and Noccaea species differing in Cd accumulation

Single Residue Mutation in Active Site of Serine Acetyltransferase Isoform 3 from Entamoeba histolytica Assists in Partial Regaining of Feedback Inhibition by Cysteine

Cyclophilin 20-3 relays a 12-oxo-phytodienoic acid signal during stress responsive regulation of cellular redox homeostasis

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