title: 20S proteasome activity is modified via S-glutathionylation based on intracellular redox status of the yeast Saccharomyces cerevisiae: implications for the degradation of oxidized proteins.
abstract: Protein S-glutathionylation is a post-translational modification that controls many cellular pathways. Recently, we demonstrated that the α5-subunit of the 20S proteasome is S-glutathionylated in yeast cells grown to the stationary phase in rich medium containing glucose, stimulating 20S core gate opening and increasing the degradation of oxidized proteins. In the present study, we evaluated the correlation between proteasomal S-glutathionylation and the intracellular redox status. The redox status was controlled by growing yeast cells in distinct carbon sources which induced respiratory (glycerol/ethanol) or fermentative (glucose) metabolism. Cells grown under glycerol/ethanol displayed higher reductive power when compared to cells grown under glucose. When purified from cells grown in glucose, 20S proteasome α5-subunit exhibited an intense anti-glutathione labeling. A higher frequency of the open catalytic chamber gate was observed in the S-glutathionylated preparations as demonstrated by transmission electron microscopy. Therefore, cells that had been grown in glucose displayed an increased ability to degrade oxidized proteins. The results of the present study suggest that 20S proteasomal S-glutathionylation is a relevant adaptive response to oxidative stress that is capable to sense the intracellular redox environment, leading to the removal of oxidized proteins via a process that is not dependent upon ubiquitylation and ATP consumption.
authors.affiliation: Laboratório de Bioquímica e Biofísica, Instituto Butantan, Brazil. Electronic address: marimasi@butantan.gov.br.
authors.forename: Marilene
authors.initials: M
authors.lastname: Demasi
authors.affiliation: Laboratório de Bioquímica e Biofísica, Instituto Butantan, Brazil.
authors.forename: Adrian
authors.initials: A
authors.lastname: Hand
authors.affiliation: Laboratório de Bioquímica e Biofísica, Instituto Butantan, Brazil.
authors.forename: Erina
authors.initials: E
authors.lastname: Ohara
authors.affiliation: Instituto de Física, Universidade de São Paulo, Brazil.
authors.forename: Cristiano L P
authors.initials: CL
authors.lastname: Oliveira
authors.affiliation: Instituto de Física, Universidade de São Paulo, Brazil.
authors.forename: Renata N
authors.initials: RN
authors.lastname: Bicev
authors.affiliation: Universidade Federal de São Paulo, Brazil.
authors.forename: Clelia A
authors.initials: CA
authors.lastname: Bertoncini
authors.affiliation: Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil.
authors.forename: Luis E S
authors.initials: LE
authors.lastname: Netto
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D005656:Fungal Proteins / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D010084:Oxidation-Reduction; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D005656:Fungal Proteins; D046988:Proteasome Endopeptidase Complex; D005978:Glutathione
keywords: 20S proteasome; Oxidized proteins; Proteolysis; Redox modulation; S-glutathionylation; S. cerevisiae