Cloning and characterization of herbicide-degrading glutathione transferases from cicer arietinum

GSTs are multifunctional enzymes that catalyze the conjugation of glutathione (GSH) to reactive electrophiles. These electrophiles are diverse and include important endogenous compounds, as well as xenobiotic chemicals, therefore GSTs play an important role in stress tolerance and herbicide detoxification. GSTs are usually active as a dimer of 24–29 kDa subunits. Each monomer of dimeric GSTs contains a G-site, at the N-terminal, capable of binding the GSH substrate and an H-site, at the C-terminal, that has xenobiotic compound-binding capabilities. Different classes of herbicides such as triazines, thiocarbamates, chloroacetanilides, diphenylethers, and aryloxyphenoxypropionates can be metabolized by GSTs. Herbicide tolerance in plants is based primarily on the differential ability of plant species to detoxify a herbicide, with the formation of a herbicide-GSH conjugate in the resistant but not in the susceptible species. The plant-specific phi and tau GSTs are primarily responsible for herbicide detoxification, showing class specificity in substrate preference. In present work, we report the cloning, kinetic and structural characterization of three members of the GST family from Cicer arietinum leaves (CaGSTs)

Sol-gel immobilization of glutathione transferase: efficient tool for bioremediation

Glutathione transferases are multi-functional enzymes with an important role in xenobiotic detoxification. They catalyse the nucleophilic addition of the sulfur atom of glutathione (γ-L-Glu-L-Cys-Gly, GSH) to the electrophilic groups of a large variety of hydrophobic molecules including organic halides, epoxides, arene oxides, α- and β-unsaturated carbonyls, organic nitrate esters, and organic thiocyanates. The conjugation of GSH to such molecules increases their solubility and reduces their toxicity. GSTs represent a versatile tool with a variety of biotechnological applications, in the field of bioremediation to clean up environmentally contaminated sites. The purpose of this project was the study of GST immobilization for the biodegradation of toxic compounds

Plant Glutathione Transferases: Structure, Antioxidant Catalytic Function and in planta Protective Role in Biotic and Abiotic Stress

Plant cytosolic glutathione transferases (GSTs) belong to an ancient enzyme superfamily with multiple and diverse functions which are important in counteracting biotic and abiotic stress. GSTs catalyze the conjugation of xenobiotics and endogenous electrophilic compounds with glutathione (GSH), leading to their detoxification. GSTs not only catalyze detoxification reactions but they are also involved in GSH-dependent isomerization reactions, in GSH-dependent reduction of organic hydroperoxides, biosynthesis of secondary metabolites, and exhibit thioltransferase and dehydroascorbate reductase activity. The applications of ‘omics’ technologies have allowed the classification of GSTs and the study of their evolution and sequence diversity, while enzymology has provided powerful insights into their catalytic role. This review focuses on plant GSTs, and attempts to give an overview of the new insights into their catalytic function and biological role in biotic and abiotic stress tolerance mechanisms in plants