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Deglutathiolation of the 20s proteasome from Saccharomyces cerevisae by the oxidoreductases glutaredoxin1 and glutaredoxin2

Grant number: 10/02898-6
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): May 01, 2010
Effective date (End): April 30, 2011
Field of knowledge:Biological Sciences - Biochemistry
Principal Investigator:Marilene Demasi
Grantee:Vanessa Simões
Home Institution: Instituto Butantan. Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

The proteasome is a complex responsible by the intracellular protein degradation, protecting the cells against oxidized, misfolded and mutant proteins. In the central core, namely 20S, are localized the catalytic sites. As already demonstrated, the 20S proteasome activity is regulated by S-glutathiolation that consists of reaction between reduced glutathione and proteasome Cys residues oxidized to the sulfenic acid (P-S-OH) resulting on a disulfide bond. This is a reversible process as suggested by reports indicating glutaredoxins and thioredoxins as the reducing enzymes. Those are thiol-proteins involved in the intracellular redox homeostase. The present project is focused on Grx1 and Grx2 that despite a high structural similarity, they differ on their ability to deglutathiolate the 20S proteasome and in the reduction of a standard substrate. In the present study, the goals are to identify and characterize the specific mechanism by which each enzyme deglutahiolate the 20S proteasome that allows the recover of its catalytic activity. (AU)