Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 frequency of X-ray-induced DNA breaks was determined in human cell lines which are deficient in glutathione synthetase and have a greatly reduced glutathione content. Hydroxyapatite chromatography was used for the estimation of the DNA breaks in cell cultures, which were derived either from lymphoblasts transformed by infection with EB virus or from fibroblasts. The dose-effect relationship for the induction of breaks when radiation exposure was made in argon, was similar to that found when exposure was made in air. In control cultures with normal glutathione content, the induction of breaks was enhanced when irradiation was made under aerobic, instead of anaerobic, conditions. Treatment of the glutathione-deficient cells with the hypoxic radiosensitizer misonidazole did not enhance the induction of breaks by radiation delivered either in air or in argon. In control cultures, radiation induction of breaks was enhanced by misonidazole under anaerobic but not under aerobic conditions. When the glutathione-deficient cells were pretreated with cysteamine however, irradiation in the absence of oxygen resulted in a decreased frequency of DNA breaks.
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PMID:Lack of oxygen effect in glutathione-deficient human cells in culture. 696 72

Using the unwinding technique in weak alkali, the induction and repair of DNA single-strand breaks was determined after aerobic and anerobic X-irradiation of human fibroblasts, obtained from a patient suffering from 5-oxoprolinuria, and from a clinically healthy control. The metabolic disorder associated with 5-oxprolinuria is a deficiency in glutathione synthetase activity resulting in a greatly reduced glutathione content in the cells. A small dose-modifying effect of oxygen (o.e.r. = 1.1) was found for these cells in comparison to an o.e.r. of 2.5 for control cells with normal glutathione content. No significant difference was found between the repair capacity of cells with normal and deficient glutathione content, and repair was nearly completed within 60 min of anoxic irradiation in each case. In contrast, after aerobic irradiation of glutathione-deficient cells repaired less than 70 per cent of the breaks during the same period. When the glutathione-deficient cells were incubated with either dithiothreitol or mercaptopropionylglycine directly after aerobic irradiation, almost complete repair was obtained within 60 Min. The data are interpreted as indicating that the repair mechanism for oxically and anoxically induced single-strand breaks is qualitatively different, and requires glutathione in the former case.
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PMID:Induction and repair of single-strand DNA breaks after X-irradiation of human fibroblasts deficient in glutathione. 697 50

Using degenerate oligodeoxyribonucleotide primers based on conserved regions of the cell-division protein FtsZ, a 220-bp fragment of DNA was amplified by the polymerase chain reaction from Anabaena PCC 7120 (Ana). This fragment, which showed significant homology with Escherichia coli ftsZ, was used as a probe to isolate a 15-kb genomic clone containing ftsZ from an Ana DNA library. Sequence analysis revealed an open reading frame (ORF) encoding a protein of 379 amino acids, with 49% identity with E. coli FtsZ. Upstream of Ana ftsZ is a small, unidentified ORF, transcribed in the same direction. An ORF lying downstream of the ftsZ coding region and transcribed in the opposite orientation, shows homology with bacterial glutathione synthetase-encoding genes. Single copies of ftsZ have been identified in Ana and two other cyanobacteria. Multiple transcripts hybridising to ftsZ were detected by Northern hybridisation.
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PMID:Cloning and sequence of ftsZ and flanking regions from the cyanobacterium Anabaena PCC 7120. 755 85

A human brain cDNA clone encoding glutathione synthetase (EC 6.3.2.3) has been sequenced and expressed in Escherichia coli. The protein is 474 amino acids in length with a subunit molecular mass of 52,352 Da. The recombinant protein exhibits glutathione synthetase activity and occurs as a homodimer. The recombinant glutathione synthetase was purified to homogeneity and had a specific activity of 1.73 mumol/min per mg of protein, an isoelectric point of 5.35 and a pH optimum between 7.0 and 7.5. Southern blots of human genomic DNA hybridized with the glutathione synthetase cDNA revealed a relatively simple pattern of strongly hybridizing fragments, indicating the absence of a large gene family and suggesting that there may be only one glutathione synthetase gene in the human genome.
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PMID:Sequencing and expression of a cDNA for human glutathione synthetase. 764 67

Heterocysts, cells specialized in nitrogen fixation in Anabaena sp. PCC 7120, lose the potential for cell division once fully differentiated. This suggests that cell division activity is differentially regulated in heterocysts and vegetative cells. FtsZ has been shown to play a crucial role in bacterial cell division. Two degenerate oligonucleotide primers were designed to detect, by polymerase chain reaction (PCR), an ftsZ homologue from the heterocystous cyanobacterium Anabaena sp. PCC 7120. A PCR-amplified DNA fragment was cloned and used as a probe to isolate the entire ftsZ gene of Anabaena sp. PCC 7120. The deduced amino acid sequence shares strong similarities with other FtsZ proteins, suggesting remarkable conservation of the FtsZ protein during evolution. An ORF downstream of ftsZ, which would be transcribed in the opposite direction compared to ftsZ, could encode a polypeptide with significant sequence similarity to the glutathione synthetase from Escherichia coli. Inactivation experiments in vivo for both ftsZ and the glutathione synthetase gene did not yield any double recombinants either in the presence or in the absence of combined nitrogen, suggesting that both genes are essential for cell growth under these conditions.
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PMID:Analysis of genes encoding the cell division protein FtsZ and a glutathione synthetase homologue in the cyanobacterium Anabaena sp. PCC 7120. 852 61

Glutathione (L-gamma-glutamyl-L-cysteinylglycine, GSH) plays an important role in the protection of plants against various types of stress caused by reactive oxygen species, gazeous pollutants, heavy metals and xenobiotics. A cDNA fragment containing the entire coding unit for glutathione synthetase (GSH2) of Arabidopsis thaliana was cloned by complementation of the methylglyoxal sensitivity of a gsh2 mutant of the yeast Saccharomyces cerevisiae. The cDNA encodes a protein of 478 amino acids (deduced Mr: 53783), bearing clear sequence similarities to GSH2 products from frog embryos (Xenopus laevis), rat kidney (Rattus norvegicus) and from the fission yeast (Schizosaccharomyces pombe). A highly conserved glycine-rich domain close to the carboxy-terminus was found in the GSH2 product and appears to be typical for eukaryotic glutathione synthetases. The Mr is similar to those of soluble animal enzymes, suggesting that the Arabidopsis gene also codes for a cytosolic protein. Genomic DNA-blot analysis indicates the presence of a single GSH2 gene. The yeast gsh2 mutant becomes resistant to methylglyoxal and cadmium after transformation with the plasmid bearing the Arabidopsis GSH2 cDNA. Moreover, this increased resistance is correlated to the restoration of GSH content from below detectability in mutants to about 50% of the wild-type levels in transformed cells.
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PMID:Cloning of Arabidopsis thaliana glutathione synthetase (GSH2) by functional complementation of a yeast gsh2 mutant. 861 43

The structural gene for glyoxalase I (GLO1) of Saccharomyces cerevisiae was identified. The GLO1 gene contained an open reading frame with 326 amino acids, and the molecular weight of the gene product (Glo1p) deduced from the DNA sequence was calculated to be 37,207.06. Glyoxalase I activity increased approximately 95-fold when the GLO1 gene was introduced into the yeast cell with a multicopy plasmid, and the resultant transformant showed the increased resistance against methylglyoxal. Since the knockout mutant of the GLO1 gene of haploid strain of S. cerevisiae was still viable, the GLO1 gene was thought to be unnecessary for growth of the yeast. The GLO1 gene was overexpressed in two kinds of glutathione-deficient mutants, gamma-glutamylcysteine synthetase-deficient (gsh1(-)) and glutathione synthetase-deficient (gsh2(-)), respectively, and the sensitivites to methylglyoxal were compared. The gsh1-deficient mutant, which could not produce glutathione at all, was hypersensitive to methylglyoxal, and overproduction of the Glo1p did not restore the growth arrest caused by exogenously added methylglyoxal. The gsh2-deficient mutant, which accumulates gamma-glutamylcysteine (an intermediate of glutathione biosynthesis), was also sensitive to methylglyoxal compared with the isogenic wild type strain, although the growth arrest caused by methylglyoxal was partially restored by overexpression of the GLO1 gene. Purified glyoxalase I from yeast could use gamma-glutamylcysteine as a substrate (kcat/Km = 1.89 x 10(7) M-1 s-1, glutathione; 3.47 x 10(4) M-1 s-1, gamma-glutamylcysteine).
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PMID:Identification of the structural gene for glyoxalase I from Saccharomyces cerevisiae. 882 31

The differential display (DD) was employed to identify the gene(s) responsible for 1,10-phenanthroline (OP)-induced apoptosis in murine tumor cells (Sun, Y., Bian, J., Wang, Y. and Jacobs, C. (1997) Oncogene 14, 385-393 [1]). An OP-inducible gene was isolated which encodes mouse glutathione synthetase (GSS). The GSS mRNA level began to increase 6 h post OP treatment and remained at a high level thereafter up to 24 h tested. Induction of GSS was found not to be associated with p53 activation. No significant induction of DNA fragmentation was detected in two murine tumor lines upon GSS transfection. This is the first observation indicating that GSS is inducible rather specifically by a metal chelator and that induction of GSS, however, is not sufficient to induce apoptosis. It may merely reflect a cellular response to OP-induced redox disturbance.
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PMID:Induction of glutathione synthetase by 1,10-phenanthroline. 918 Feb 59

Severe glutathione synthetase (GS) deficiency is a rare genetic disorder with neonatal onset. The enzymatic block of the gamma-glutamyl cycle leads to a generalized glutathione deficiency. Clinically affected patients present with severe metabolic acidosis, 5-oxoprolinuria, increased rate of hemolysis and defective function of the central nervous system. The disorder is inherited in an autosomal recessive mode and, until recently, the molecular basis has remained unknown. We have sequenced 18 GS alleles associated with enzyme deficiency and we detected missense mutations by direct sequencing of cDNAs and genomic DNA. In total, 13 different mutations were identified. Four patients were found to be compound heterozygotes and two individuals were apparently homozygous. Reduced enzymatic activities were demonstrated in recombinant protein expressed from cDNAs in four cases with different missense mutations. The results from biochemical analysis of patient specimens, supported by the properties of the expressed mutant proteins, indicate that a residual activity is present in affected individuals. Our results suggest that complete loss of function of both GS alleles is probably lethal. It is postulated that missense mutations will account for the phenotype in the majority of patients with severe GS deficiency.
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PMID:Missense mutations in the human glutathione synthetase gene result in severe metabolic acidosis, 5-oxoprolinuria, hemolytic anemia and neurological dysfunction. 921 86

The gene homologous to glutathione synthetase of Escherichia coli was inactivated in the cyanobacterium Synechococcus sp. PCC 7942. The region of genomic DNA including the mutation site was isolated from the mutant by plasmid rescue and the native gene of the wild-type was cloned from a genomic DNA library of the wild-type using the flanking DNA as a probe. The wild-type gene, designated gshB, encodes a polypeptide of 323 amino acids with a molecular mass of 35 kDa. The deduced amino acid sequence resembles glutathione synthetases of bacteria, but not those of higher organisms. When gshB was overexpressed in E. coli, glutathione synthetase activity was increased markedly in the E. coli extract. In addition, the Synechococcus sp. PCC 7942 gshB mutants had lost their ability to synthesize glutathione. These findings demonstrate that the gshB gene of Synechococcus sp. PCC 7942 is a structural gene for glutathione synthetase and is involved in the biosynthesis of glutathione.
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PMID:The gshB gene in the cyanobacterium Synechococcus sp. PCC 7942 encodes a functional glutathione synthetase. 930 72


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