The Saccharomyces cerevisiae genome encodes three proteins that display similarities with human GSTOs (Omega class glutathione S-transferases) hGSTO1-1 and hGSTO2-2. The three yeast proteins have been named Gto1, Gto2 and Gto3, and their purified recombinant forms are active as thiol transferases (glutaredoxins) against HED (β-hydroxyethyl disulphide), as dehydroascorbate reductases and as dimethylarsinic acid reductases, while they are not active against the standard GST substrate CDNB (1-chloro-2,4-dinitrobenzene). Their glutaredoxin activity is also detectable in yeast cell extracts. The enzyme activity characteristics of the Gto proteins contrast with those of another yeast GST, Gtt1. The latter is active against CDNB and also displays glutathione peroxidase activity against organic hydroperoxides such as cumene hydroperoxide, but is not active as a thiol transferase. Analysis of point mutants derived from wild-type Gto2 indicates that, among the three cysteine residues of the molecule, only the residue at position 46 is required for the glutaredoxin activity. This indicates that the thiol transferase acts through a monothiol mechanism. Replacing the active site of the yeast monothiol glutaredoxin Grx5 with the proposed Gto2 active site containing Cys46 allows Grx5 to retain some activity against HED. Therefore the residues adjacent to the respective active cysteine residues in Gto2 and Grx5 are important determinants for the thiol transferase activity against small disulphide-containing molecules.
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Research Article|
August 15 2006
Saccharomyces cerevisiae cells have three Omega class glutathione S-transferases acting as 1-Cys thiol transferases
Ana Garcerá;
Ana Garcerá
1Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, Montserrat Roig 2, 25008-Lleida, Spain
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Lina Barreto;
Lina Barreto
1Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, Montserrat Roig 2, 25008-Lleida, Spain
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Lidia Piedrafita;
Lidia Piedrafita
1Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, Montserrat Roig 2, 25008-Lleida, Spain
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Jordi Tamarit;
Jordi Tamarit
1Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, Montserrat Roig 2, 25008-Lleida, Spain
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Enrique Herrero
Enrique Herrero
1
1Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, Montserrat Roig 2, 25008-Lleida, Spain
1To whom correspondence should be addressed (email enric.herrero@cmb.udl.es).
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Publisher: Portland Press Ltd
Received:
January 05 2006
Revision Received:
May 18 2006
Accepted:
May 18 2006
Accepted Manuscript online:
May 18 2006
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2006
Biochem J (2006) 398 (2): 187–196.
Article history
Received:
January 05 2006
Revision Received:
May 18 2006
Accepted:
May 18 2006
Accepted Manuscript online:
May 18 2006
Citation
Ana Garcerá, Lina Barreto, Lidia Piedrafita, Jordi Tamarit, Enrique Herrero; Saccharomyces cerevisiae cells have three Omega class glutathione S-transferases acting as 1-Cys thiol transferases. Biochem J 1 September 2006; 398 (2): 187–196. doi: https://doi.org/10.1042/BJ20060034
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