Rat lung glutathione S-transferases. Evidence for two distinct types of 22000-Mr subunits.
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ABSTRACT:
SUBMITTER: Singh SV
PROVIDER: S-EPMC1144088 | biostudies-other | 1984 Aug
REPOSITORIES: biostudies-other
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Project description:Human brain contains one cationic (pI8.3) and two anionic (pI5.5 and 4.6) forms of glutathione S-transferase. The cationic form (pI8.3) and the less-anionic form (pI5.5) do not correspond to any of the glutathione S-transferases previously characterized in human tissues. Both of these forms are dimers of 26500-Mr subunits; however, immunological and catalytic properties indicate that these two enzyme forms are different from each other. The cationic form (pI8.3) cross-reacts with antibodies raised against cationic glutathione S-transferases of human liver, whereas the anionic form (pI5.5) does not. Additionally, only the cationic form expresses glutathione peroxidase activity. The other anionic form (pI4.6) is a dimer of 24500-Mr and 22500-Mr subunits. Two-dimensional gel electrophoresis demonstrates that there are three types of 26500-Mr subunits, two types of 24500-Mr subunits and two types of 22500-Mr subunits present in the glutathione S-transferases of human brain.
| S-EPMC1144600 | biostudies-other
Project description:Two types of 25 000-Mr subunits are present in rat lung glutathione S-transferase I (pI 8.8). These subunits, designated Yc and Yc', are immunologically and functionally distinct from each other. The homodimers YcYc (pI 10.4) and Yc'Yc' (pI 7.6) obtained by hybridization in vitro of the two subunits of glutathione S-transferase I (pI 8.8) were isolated and characterized. Results of these studies indicate that only the Yc subunits express glutathione peroxidase activity and cross-react with the antibodies raised against glutathione S-transferase B (YaYc) or rat liver. The Yc' subunits do not express glutathione peroxidase activity and do not cross-react with the antibodies raised against glutathione S-transferase B of rat liver. The amino acid compositions of these two subunits are also different. These two subunits can also be separated by the two-dimensional gel electrophoresis of glutathione S-transferase I (pI 8.8) of rat lung.
| S-EPMC1144432 | biostudies-other
Project description:The 55 Arabidopsis glutathione transferases (GSTs) are, with one microsomal exception, a monophyletic group of soluble enzymes that can be divided into phi, tau, theta, zeta, lambda, dehydroascorbate reductase (DHAR) and TCHQD classes. The populous phi and tau classes are often highly stress inducible and regularly crop up in proteomic and transcriptomic studies. Despite much study on their xenobiotic-detoxifying activities their natural roles are unclear, although roles in defence-related secondary metabolism are likely. The smaller DHAR and lambda classes are likely glutathione-dependent reductases, the zeta class functions in tyrosine catabolism and the theta class has a putative role in detoxifying oxidised lipids. This review describes the evidence for the functional roles of GSTs and the potential for these enzymes to perform diverse functions that in many cases are not "glutathione transferase" activities. As well as biochemical data, expression data from proteomic and transcriptomic studies are included, along with subcellular localisation experiments and the results of functional genomic studies.
| S-EPMC3244946 | biostudies-literature
Project description:SummaryThe soluble glutathione transferases (GSTs, EC 2.5.1.18) are encoded by a large and diverse gene family in plants, which can be divided on the basis of sequence identity into the phi, tau, theta, zeta and lambda classes. The theta and zeta GSTs have counterparts in animals but the other classes are plant-specific and form the focus of this article. The genome of Arabidopsis thaliana contains 48 GST genes, with the tau and phi classes being the most numerous. The GST proteins have evolved by gene duplication to perform a range of functional roles using the tripeptide glutathione (GSH) as a cosubstrate or coenzyme. GSTs are predominantly expressed in the cytosol, where their GSH-dependent catalytic functions include the conjugation and resulting detoxification of herbicides, the reduction of organic hydroperoxides formed during oxidative stress and the isomerization of maleylacetoacetate to fumarylacetoacetate, a key step in the catabolism of tyrosine. GSTs also have non-catalytic roles, binding flavonoid natural products in the cytosol prior to their deposition in the vacuole. Recent studies have also implicated GSTs as components of ultraviolet-inducible cell signaling pathways and as potential regulators of apoptosis. Although sequence diversification has produced GSTs with multiple functions, the structure of these proteins has been highly conserved. The GSTs thus represent an excellent example of how protein families can diversify to fulfill multiple functions while conserving form and structure.
| S-EPMC139027 | biostudies-literature
Project description:Plants, as sessile organisms, can suffer serious growth and developmental consequences under cold stress conditions. Glutathione transferases (GSTs, EC 2.5.1.18) are ubiquitous and multifunctional conjugating proteins, which play a major role in stress responses by preventing oxidative damage by reactive oxygen species (ROS). Currently, understanding of their function(s) during different biochemical and signaling pathways under cold stress condition remain unclear. In this study, using combined computational strategy, we identified 65 Brassica oleracea glutathione transferases (BoGST) and characterized them based on evolutionary analysis into 11 classes. Inter-species and intra-species duplication was evident between BoGSTs and Arabidopsis GSTs. Based on localization analyses, we propose possible pathways in which GST genes are involved during cold stress. Further, expression analysis of the predicted putative functions for GST genes were investigated in two cold contrasting genotypes (cold tolerance and susceptible) under cold condition, most of these genes were highly expressed at 6 h and 1 h in the cold tolerant (CT) and cold susceptible (CS) lines, respectively. Overall, BoGSTU19, BoGSTU24, BoGSTF10 are candidate genes highly expressed in B. oleracea. Further investigation of GST superfamily in B. oleracea will aid in understanding complex mechanism underlying cold tolerance in plants.
| S-EPMC5000609 | biostudies-literature
Project description:In humans, the glutathione S-transferases (GST) protein family is composed of seven members that present remarkable structural similarity and some degree of overlapping functionalities. GST proteins are crucial antioxidant enzymes that regulate stress-induced signaling pathways. Interestingly, overactive GST proteins are a frequent feature of many human cancers. Recent evidence has revealed that the biology of most GST proteins is complex and multifaceted and that these proteins actively participate in tumorigenic processes such as cell survival, cell proliferation, and drug resistance. Structural and pharmacological studies have identified various GST inhibitors, and these molecules have progressed to clinical trials for the treatment of cancer and other diseases. In this review, we discuss recent findings in GST protein biology and their roles in cancer development, their contribution in chemoresistance, and the development of GST inhibitors for cancer treatment.
| S-EPMC8146591 | biostudies-literature
Project description:Liver cytosol from mice fed on a normal diet contains Alpha-class glutathione S-transferase (GST) subunits of Mr 25,800, Mu-class GST subunits of Mr 26,400 and Pi-class GST subunits of Mr 24,800. Feeding female mice with a diet containing the anticarcinogenic antioxidant butylated hydroxyanisole (BHA) causes induction of the constitutively expressed Mu-class and Pi-class subunits. BHA also induces an Alpha-class GST comprising subunits of Mr 25,600, which is not expressed at detectable levels in normal mouse liver [McLellan & Hayes (1989) Biochem. J. 263, 393-402]. Data are now presented that show that administration of the anticarcinogen beta-naphthoflavone (BNF), like BHA, induces the Alpha-class 25,600-Mr subunits but not the constitutive Alpha-class GST with subunits of Mr 25,800. The effects of BNF on expression of hepatic GST were studied in both DBA/2 and C57BL/6 mice; these studies revealed a preferential induction of the Alpha-class 25,600-Mr subunits and of the Pi-class 24,800-Mr subunits in those mice in possession of a functional Ah receptor. The BHA/BNF-inducible Alpha-class GST can be resolved into two separate, non-interconvertible peaks by reverse-phase h.p.l.c. Automated amino acid sequence analysis of CNBr-derived peptides from each of these h.p.l.c.-purified peaks showed that the peaks contained at least two very similar subunits. These have been named Ya1 and Ya2. The amino acid sequence of the Ya1 subunit was compared with sequences deduced from a genomic clone, lambda mYa1 (Daniel, Sharon, Tichauer & Sarid (1987) DNA 6, 317-324], and a cDNA clone, pGT41 [Pearson, Reinhart, Sisk, Anderson & Adler (1988) J. Biol. Chem. 263, 13324-13332]. Our data suggest that the Ya1 subunit represents the subunit encoded by the genomic clone, lambda mYa1. Sequence analysis of the constitutive Alpha-class Ya3 subunit (Mr 25,800) shows that, although it is a member of the same gene family as the Ya1 and Ya2 subunits, it represents a distinct sub-family of Alpha-class GST, containing subunits that are more similar to rat Yc. Our data indicate that, of these Alpha-class GST subunits, the two with Mr 25,600 (Ya1 and Ya2) are selectively induced by BHA or BNF in mouse liver; neither BHA nor BNF induces significantly the GST subunit with Mr 25,800 (Ya3).
| S-EPMC1151114 | biostudies-other
Project description:The Marin strain of Culex pipiens Say is a pyrethroid-resistant population that was collected in Marin County, California, in 2001 and subsequently maintained in the laboratory under regular permethrin exposure.In this study, two cDNAs, CpGSTd1 and CpGSTd2, encoding glutathione S-transferase (GST) were cloned from Cx. pipiens Marin. Phylogenetic analysis of the deduced amino acid sequences, CpGSTD1 and CpGSTD2, of these genes indicated that they belong to the Delta class of insect GSTs. The nucleotide and deduced amino acid sequences of CpGSTd1 and CpGSTd2 were 59 and 48% identical respectively. CpGSTD1 and CpGSTD2 were expressed in Escherichia coli and purified by affinity chromatography. The recombinant GSTs exhibited unique selectivity towards the general GST substrates 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB), and also differed in their sensitivity to known inhibitors of GSTs. CpGSTD1 exhibited peroxidase activity with cumene hydroperoxide, while CpGSTD2 appeared to lack this activity. CpGSTD1 was able to metabolize 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), while DDT metabolism by CpGSTD2 was not detectable. CpGSTD1 and CpGSTD2 showed no detectable metabolism of permethrin. Gene expression of CpGSTd1 and CpGSTd2 in Marin mosquitoes was elevated about twofold in comparison with that found in a pyrethroid-sensitive mosquito strain.The results indicate that CpGSTD1 and CpGSTD2 have unique biochemical characteristics, but they do not appear to play major roles in permethrin resistance in Marin mosquitoes.
| S-EPMC3583349 | biostudies-literature
Project description:Glutathione S-transferases (GSTs), detoxification enzymes that catalyze the addition of glutathione (GSH) to diverse electrophilic molecules, are often overexpressed in various tumor cells. While fluorescent probes for GSTs have often adopted the 2,4-dinitrobenzenesulfonyl (DNs) group as the receptor unit, they usually suffer from considerable background reaction noise with GSH due to excessive electron deficiency. However, weakening this reactivity is generally accompanied by loss of sensitivity for GSTs, and therefore, finely turning down the reactivity while maintaining certain sensitivity is critical for developing a practical probe. Here, we report a rational semiquantitative strategy for designing such a practical two-photon probe by introducing a parameter adopted from the conceptual density functional theory (CDFT), the local electrophilicity ω k , to characterize this reactivity. As expected, kinetic studies established ω k as efficient to predict the reactivity with GSH, and probe NI3 showing the best performance was successfully applied to detecting GST activities in live cells and tissue sections with high sensitivity and signal-to-noise ratio. Photoinduced electron transfer of naphthalimide-based probes, captured by femtosecond transient absorption for the first time and unraveled by theoretical calculations, also contributes to the negligible background noise.
| S-EPMC7114728 | biostudies-literature
Project description:In addition to their well-established role in detoxication, glutathione transferases (GSTs) have other biological functions. We are focusing on the ketosteroid isomerase activity, which appears to contribute to steroid hormone biosynthesis in mammalian tissues. A highly efficient GST A3-3 is present in some, but not all, mammals. The alpha class enzyme GST A3-3 in humans and the horse shows the highest catalytic efficiency with kcat/Km values of approximately 107 M-1s-1, ranking close to the most active enzymes known. The expression of GST A3-3 in steroidogenic tissues suggests that the enzyme has evolved to support the activity of 3β-hydroxysteroid dehydrogenase, which catalyzes the formation of 5-androsten-3,17-dione and 5-pregnen-3,20-dione that are substrates for the double-bond isomerization catalyzed by GST A3-3. The dehydrogenase also catalyzes the isomerization, but its kcat of approximately 1 s-1 is 200-fold lower than the kcat values of human and equine GST A3-3. Inhibition of GST A3-3 in progesterone-producing human cells suppress the formation of the hormone. Glutathione serves as a coenzyme contributing a thiolate as a base in the isomerase mechanism, which also involves the active-site Tyr9 and Arg15. These conserved residues are necessary but not sufficient for the ketosteroid isomerase activity. A proper assortment of H-site residues is crucial to efficient catalysis by forming the cavity binding the hydrophobic substrate. It remains to elucidate why some mammals, such as rats and mice, lack GSTs with the prominent ketosteroid isomerase activity found in certain other species. Remarkably, the fruit fly Drosophila melanogaster, expresses a GSTE14 with notable steroid isomerase activity, even though Ser14 has evolved as the active-site residue corresponding to Tyr9 in the mammalian alpha class.
| S-EPMC8645602 | biostudies-literature