Structure and Antioxidant Catalytic Function of Plant Glutathione Transferases

Abstract

Plant cytosolic glutathione transferases (GSTs) are an ancient enzyme superfamily with multiple and diverse functions which are important in counteracting biotic and abiotic stress. GSTs play an important role in catalyzing the conjugation of xenobiotics and endogenous electrophilic compounds with glutathione (GSH), such as pesticides, chemical carcinogens, environmental pollutants, which leads 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 formed during oxidative stress, biosynthesis of sulfur-containing secondary metabolites, and exhibit thioltransferase and dehydroascorbate reductase activity. This review focuses on plant GSTs, and attempts to give an overview of the new insights into the catalytic function and structural biology of these enzymes.

Catalytic features and crystal structure of a tau class glutathione transferase from Glycine max specifically upregulated in response to soybean mosaic virus infections

“…Plant glutathione S-transferases (GSTs; EC 2.5.1.18) are enzymes that catalyze the conjugation of reduced glutathione (GSH; γ-Glu-Cys-Gly) to electrophilic centers of a wide variety of, mainly hydrophobic, compounds, both endogenous and xenobiotic [1][2][3][4]. GSTs are implicated in pesticide detoxification [5][6][7], in responses to abiotic and biotic stress (infection, heavy metals, UV radiation, etc) [8][9][10][11], as well as in hormonal regulation and developmental change [12][13][14][15][16].…”

“…Based on a variety of criteria (e.g. sequence relatedness, immunological, kinetic and structural properties), plant soluble GSTs can be subdivided to distinct classes: phi (F), tau (U), zeta (Z), theta (T), lambda (λ), dehydroascorbate reductase (DHAR), and tetrachlorohydroquinone dehalogenase (TCHQD) [1,2,12,13]. The tau class, in particular, is the most abundant of all GST classes and its members play important roles in stress tolerance and secondary metabolism as well as catalyzing the detoxification of herbicides in crops and weeds [9,[13][14][15][17][18][19].…”

Adding Functions to Biomaterial Surfaces through Protein Incorporation

“…Affinity improvement of antibodies is achieved via one of numerous technologies which mimic natural affinity maturation through an iterative cycle of mutagenesis to increase diversity and isolation of molecules with increasing affinities from the protein library ( Figure 5). In vitro mutagenic approaches can be random, such as those utilizing mutator bacterial strains or chemical mutagens, [152] targeted to regions of the molecule such as a binding pocket by "error-prone" PCR or saturation mutagenesis, [153] or based on molecular evolution techniques. [154] These approaches frequently yield antibody variants with affinities far in excess of natural antibodies, sometimes 1,000s of times higher than the parent molecules.…”

Inhibition of human glutathione transferases by pesticides: Development of a simple analytical assay for the quantification of pesticides in water

“…This amount is sufficient for more than 2.4 × 10 5 assays. The enzyme-based assays have potential advantages over bioassays and other analytical methods based on HPLC and GC/MS [26,27] in terms of lower cost and technical complexity. Moreover, they provide reasonable sensitivity for certain applications, such as the direct determination of pesticide residues in water samples.…”

“…Each subunit (22)(23)(24)(25)(26)(27)(28)(29) contains an active site that consists of a GSH-binding site (G-site) in the Nterminal domain and a site that binds the hydrophobic substrate (H-site) in the C-terminal domain [3][4][5][6]. The H-site shows low homology between isoenzymes within each class and amongst different classes, and can bind a large variety of substrates that differ in size, structure and hydrophobicity.…”