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Glutathione Synthetase (glutathione + synthetase)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

Cadmium induced oxidative stress influence on glutathione metabolic genes of Camellia sinensis (L.) O. Kuntze

ENVIRONMENTAL TOXICOLOGY, Issue 4 2007
Prashant Mohanpuria
Abstract Glutathione, a tripeptide with sulfhydryl (-SH) group is a very crucial compound primarily involved in redox balance maintenance of the cellular environment. In this study, we monitored the influence of Cd exposure on the transcript levels of glutathione metabolic genes in bud tissues, the youngest leaf, of Camellia sinensis L. In addition, some physiochemical parameters were also studied. Cd exposure decreased chlorophyll and protein contents, while increase was observed in lipid peroxidation upon Cd treatments. These changes were found to be concentration and duration dependent, indicating the occurrence of oxidative stress upon Cd exposure. The transcript levels of glutathione biosynthetic genes viz. ,-glutamylcysteine synthetase (,-ECS) and glutathione synthetase (GSHS) increased upon Cd exposure. Furthermore, transcript levels of glutathione reductase (GR), an enzyme involved in reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH), also showed upregulation on Cd exposure. However, the transcript levels of glutathione-S-transferase (GST), an enzyme involved in forming metal,GSH complex and help in sequestration of high levels of metal ions to vacuole, did not show any change on Cd treatment. This study document that Cd exposure induces oxidative stress in Camellia sinensis and the upregulation in transcript levels of glutathione metabolic genes except GST have suggested the role of these enzymes in the protection of plants from high level Cd exposure. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 368,374, 2007. [source]

Sulfur assimilation and glutathione metabolism under cadmium stress in yeast, protists and plants

FEMS MICROBIOLOGY REVIEWS, Issue 4 2005
David Mendoza-Cózatl
Abstract Glutathione (,-glu-cys-gly; GSH) is usually present at high concentrations in most living cells, being the major reservoir of non-protein reduced sulfur. Because of its unique redox and nucleophilic properties, GSH serves in bio-reductive reactions as an important line of defense against reactive oxygen species, xenobiotics and heavy metals. GSH is synthesized from its constituent amino acids by two ATP-dependent reactions catalyzed by ,-glutamylcysteine synthetase and glutathione synthetase. In yeast, these enzymes are found in the cytosol, whereas in plants they are located in the cytosol and chloroplast. In protists, their location is not well established. In turn, the sulfur assimilation pathway, which leads to cysteine biosynthesis, involves high and low affinity sulfate transporters, and the enzymes ATP sulfurylase, APS kinase, PAPS reductase or APS reductase, sulfite reductase, serine acetyl transferase, O -acetylserine/O -acetylhomoserine sulfhydrylase and, in some organisms, also cystathionine ,-synthase and cystathionine ,-lyase. The biochemical and genetic regulation of these pathways is affected by oxidative stress, sulfur deficiency and heavy metal exposure. Cells cope with heavy metal stress using different mechanisms, such as complexation and compartmentation. One of these mechanisms in some yeast, plants and protists is the enhanced synthesis of the heavy metal-chelating molecules GSH and phytochelatins, which are formed from GSH by phytochelatin synthase (PCS) in a heavy metal-dependent reaction; Cd2+ is the most potent activator of PCS. In this work, we review the biochemical and genetic mechanisms involved in the regulation of sulfate assimilation-reduction and GSH metabolism when yeast, plants and protists are challenged by Cd2+. [source]

Crystallization and preliminary crystallographic analysis of bifunctional ,-glutamylcysteine synthetase,glutatione synthetase from Streptococcus agalactiae

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2009
Yasunori Nakashima
,-Glutamylcysteine synthetase,glutathione synthetase (,GCS-GS) is a bifunctional enzyme that catalyzes two consecutive steps of ATP-dependent peptide formation in glutathione biosynthesis. Streptococcus agalactiae,GCS-GS is a target for the development of potential therapeutic agents. ,GCS-GS was crystallized using the sitting-drop vapour-diffusion method. The crystals grew to dimensions of 0.3 × 0.2 × 0.2,mm under reducing conditions with 5,mM TCEP. X-ray data were collected to 2.8,Ĺ resolution from a tetragonal crystal that belonged to space group I41. [source]

Augmented biosynthesis of cadmium sulfide nanoparticles by genetically engineered Escherichia coli

BIOTECHNOLOGY PROGRESS, Issue 5 2009
Yen-Lin Chen
Abstract Microorganisms can complex and sequester heavy metals, rendering them promising living factories for nanoparticle production. Glutathione (GSH) is pivotal in cadmium sulfide (CdS) nanoparticle formation in yeasts and its synthesis necessitates two enzymes: ,-glutamylcysteine synthetase (,-GCS) and glutathione synthetase (GS). Hereby, we constructed two recombinant E. coli ABLE C strains to over-express either ,-GCS or GS and found that ,-GCS over-expression resulted in inclusion body formation and impaired cell physiology, whereas GS over-expression yielded abundant soluble proteins and barely impeded cell growth. Upon exposure of the recombinant cells to cadmium chloride and sodium sulfide, GS over-expression augmented GSH synthesis and ameliorated CdS nanoparticles formation. The resultant CdS nanoparticles resembled those from the wild-type cells in size (2,5 nm) and wurtzite structures, yet differed in dispersibility and elemental composition. The maximum particle yield attained in the recombinant E. coli was ,2.5 times that attained in the wild-type cells and considerably exceeded that achieved in yeasts. These data implicated the potential of genetic engineering approach to enhancing CdS nanoparticle biosynthesis in bacteria. Additionally, E. coli -based biosynthesis offers a more energy-efficient and eco-friendly method as opposed to chemical processes requiring high temperature and toxic solvents. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]