Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.2.3 (glutathione synthetase)
 678 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The intercellular distribution of the enzymes and metabolites of assimilatory sulfate reduction and glutathione synthesis was analyzed in maize (Zea mays L. cv LG 9) leaves. Mesophyll cells and strands of bundle-sheath cells from second leaves of 11-d-old maize seedlings were obtained by two different mechanical-isolation methods. Cross-contamination of cell preparations was determined using ribulose bisphosphate carboxylase (EC 4.1.1.39) and nitrate reductase (EC 1.6.6.1) as marker enzymes for bundle-sheath and mesophyll cells, respectively. ATP sulfurylase (EC 2.7.7.4) and adenosine 5'-phosphosulfate sulfotransferase activities were detected almost exclusively in the bundle-sheath cells, whereas GSH synthetase (EC 6.3.2.3) and cyst(e)ine, gamma-glutamylcysteine, and glutathione were located predominantly in the mesophyll cells. Feeding experiments using [35S]sulfate with intact leaves indicated that cyst(e)ine was the transport metabolite of reduced sulfur from bundle-sheath to mesophyll cells. This result was corroborated by tracer experiments, which showed that isolated bundle-sheath strands fed with [35S]sulfate secreted radioactive cyst(e)ine as the sole thiol into the resuspending medium. The results presented in this paper show that assimilatory sulfate reduction is restricted to the bundle-sheath cells, whereas the formation of glutathione takes place predominantly in the mesophyll cells, with cyst(e)ine functioning as a transport metabolite between the two cell types.
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PMID:Cyst(e)ine is the transport metabolite of assimilated sulfur from bundle-sheath to mesophyll cells in maize leaves 953 48

Cadmium (Cd) is a strongly phytotoxic heavy metal, which inhibits plant growth and even leads to plant death. The main symptoms of Cd(2+) toxicity to plants are stunting and chlorosis. Plant has developed some functions for Cd(2+) tolerance, which include cell wall binding, chelation with phytochelatins (PCs), compartmentation of Cd(2+) in vacuole, and enrichment in leaf trichomes. However, Cd(2+) tolerance in plant is more likely involved in an integrated network of multiple response processes than several isolated functions cited above. In the network, the processes of sulfur metabolism, antioxidative response, and Cd(2+) transport across plasma and vacuole membrane in plant are closely related with Cd(2+) tolerance in plant. The processes of sulfur uptake, assimilation and sequential sulfur metabolism in plant respond to Cd(2+) stress. The expression of sulfur transporters with varied affinity was changed in different ways under Cd(2+) stress, and the high expression of ATP sulfurylase (APS) and adenosine 5' phosphosulfate reductase (APR), which may help to keep the supply of S(2-) for cysteine (Cys) synthesis. The efficiency of Cys synthesis may function in Cd(2+) detoxification, and the up-regulated expression of Ser acetyltransferase (SAT) and O-acetyl-ser (thiol)-lyase (OASTL) has been found in some Cd(2+) treated plants. Reduced glutathione (GSH) is an important antioxidant and the precursor of PCs, glutamylcysteine synthetase (GCS) and glutathione synthetase (GS) catalyze GSH synthesis from Cys, overexpression of the two enzymes can improve Cd(2+) tolerance in plant. PCs are more important Cd(2+) chelators than metallothioneins (MTs) in plants, and the expression of phytochelatin synthase (PCS) responds to Cd(2+) stress. Plant antioxidative system also contributes to Cd(2+) tolerance. The antioxidative response to Cd(2+)-induced oxidative stress varies in different plants and tissues and is also Cd(2+) concentration dependent, and the Cd hyperaccumulator plants show strong tolerance to oxidative stress. Some genes encoded metal transporters with Cd(2+) substrate specificity at plasma and vacuole membranes, which have been isolated and characterized in recent years. These genes play critical roles in Cd(2+) translocation, allocation, and compartmentation in plants. Despite the great progresses made in the field in recent years, there are still some issues which need further exploration, such as the detail of signal transduction and the responses of gene regulation to Cd(2+), the rhizosphere activation and root adsorption to soil Cd(2+), Cd(2+) trafficking in xylem and phloem, Cd(2+) translocation to fruit and seed, and the possible presence of a high-affinity Cd(2+) transporter in Cd hyperaccumulators.
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PMID:[Mechanisms of heavy metal cadmium tolerance in plants]. 1647 24

In roots and shoots of pea plants (Pisum sativum L.) cultivated with CdCl(2) concentrations up to 50 micromolar, growth, the content of total acid soluble thiols, and the activity of glutathione synthetase (EC 6.3.2.3) and of adenosine 5'-phosphosulfate sulfotransferase were measured. In addition, the occurrence of Cd-binding peptides (phytochelatins) and the contents of glutathione and cysteine were determined in roots of plants exposed to 20 micromolar Cd and/or 1 millimolar buthionine sulfoximine, an inhibitor of glutathione synthesis. An appreciable increase in activity of glutathione synthetase at 20 and 50 micromolar Cd and of adenosine 5'-phosphosulfate sulfotransferase at 5 micromolar and higher Cd concentrations was detected in the roots. Most of the additional thiols formed due to Cd treatment were eluted from a gel filtration HPLC column together with Cd, indicating the presence of phytochelatins. In plants treated with buthionine sulfoximine and Cd, no phytochelatins could be detected but the cysteine content increased 21-fold. Additionally, a larger increase in both enzyme activities occurred than with Cd alone. Taken together, our results are consistent with the hypothesis that glutathione is a precursor for phytochelatin synthesis.
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PMID:Regulation of Glutathione Synthesis by Cadmium in Pisum sativum L. 1666 59