The 20 S proteasome core purified from Saccharomyces cerevisiae is inhibited by reduced glutathione (GSH), cysteine (Cys), or the GSH precursor gamma-glutamylcysteine. Chymotrypsin-like activity was more affected by GSH than trypsin-like activity, whereas the peptidylglutamyl-hydrolyzing activity (caspase-like) was not inhibited by GSH. Cys-sulfenic acid formation in the 20 S core was demonstrated by spectral characterization of the Cys-S(O)-4-nitrobenzo-2-oxa-1,3-diazole adduct, indicating that 20 S proteasome Cys residues might react with reduced sulfhydryls (GSH, Cys, and gamma-glutamylcysteine) through the oxidized Cys-sulfenic acid form. S-Glutahionylation of the 20 S core was demonstrated in vitro by GSH-biotin incorporation and by decreased alkylation with monobromobimane. Compounds such as N-ethylmaleimide (-S-sulfhydril H alkylating), dimedone (-SO sulfenic acid H reactant), or 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (either -SH or -SOH reactant) highly inhibited proteasomal chymotrypsin-like activity. In vivo experiments revealed that 20 S proteasome extracted from H(2)O(2)-treated cells showed decreased chymotrypsin-like activity accompanied by S-glutathionylation as demonstrated by GSH release from the 20 S core after reduction with NaBH(4). Moreover, cells pretreated with H(2)O(2) showed decreased reductive capacity assessed by determination of the GSH/oxidized glutathione ratio and increased protein carbonyl levels. The present results indicate that at the physiological level the yeast 20 S proteasome is regulated by its sulfhydryl content, thereby coupling intracellular redox signaling to proteasome-mediated proteolysis.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|