Glutaredoxin participates in the reduction of peroxides by the mitochondrial 1-CYS peroxiredoxin in Saccharomyces cerevisiae.
The mechanism for regeneration of the active-site "peroxidatic" cysteine in 1-Cys peroxiredoxins is a matter of debate. Saccharomyces cerevisiae Prx1 is a mitochondrial enzyme belonging to the 1-Cys Prx, whereas Grx2 is involved in antioxidant defense and localizes at the mitochondria, so we hypothesized that it could be a perfect candidate to resolve the sulfenate in Prx1 with GSH. In vitro experiments with purified Prx1p and Grx2p demonstrate that Grx2p, at concentrations <1 microM, coupled to GSH, is a very efficient thiolic intermediary for the reduction of the peroxidatic Cys in Prx1p. Prx1p forms oligomeric aggregates natively, but depolymerizes down to a dimeric state after treatment with GSH. The catalytic cycle involves glutathionylation of dimeric Prx1p and deglutathionylation by Grx2p. Dihydrolipoamide, a genuine mitochondrial dithiol, can efficiently substitute for GSH. The activity is highest at alkaline pH, consistent with the conditions of active respiring mitochondria, and the process is highly specific for 1-Cys Prx because Grx2p is totally inactive with human PRX1, a typical 2-Cys Prx, as opposed to the promiscuity of Trx. Our results suggest that although Trx is the reductant involved in the reduction of peroxides by 2-Cys-Prx, Grx might be the natural resolving partner of 1-Cys Prx through a monothiolic mechanism.
Pedrajas
José Rafael
JR
Department of Experimental Biology, University of Jaén, Spain.
Padilla
C Alicia
CA
McDonagh
Brian
B
Bárcena
José Antonio
JA
D020134:Catalytic Domain; D003545:Cysteine / Q000378:metabolism; D004583:Electrons; D054477:Glutaredoxins / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D010545:Peroxides / Q000378:metabolism*; D054464:Peroxiredoxins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism
D054477:Glutaredoxins; C527885:Grx2 protein, S cerevisiae; D010545:Peroxides; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D013879:Thioredoxins; C410041:PRX1 protein, S cerevisiae; D010544:Peroxidases; D054464:Peroxiredoxins; D005978:Glutathione; D003545:Cysteine; D019803:Glutathione Disulfide