Abstract
Overexpression of the ubiquitin-conjugating enzyme Cdc34 conferred strong cadmium resistance on budding yeast. Proteasome activity, which is involved in the degradation of ubiquitinated proteins, was not essential for the acquisition of resistance to cadmium. The overexpression of Cdc34 accelerated the ubiquitination of the transcription factor Met4 and reduced expression of MET25 gene, which is a target of Met4. A MET25-disrupted strain of yeast was more resistant to cadmium than was the wild-type strain, but overexpression of Cdc34 in the MET25-disrupted cells did not affect sensitivity to cadmium. Met25 is an enzyme that catalyzes the synthesis of homocysteine from sulfide (S(2-)) and O-acetylhomocysteine and we detected the increased production of S(2-) upon overexpression of Cdc34. Our results suggest that overexpression of Cdc34 inactivates Met4 and interferes with expression of the MET25, with subsequent production of CdS, which has low toxicity, and, thus, a decrease in the cadmium toxicity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Anaphase-Promoting Complex-Cyclosome
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Basic-Leucine Zipper Transcription Factors / genetics
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Basic-Leucine Zipper Transcription Factors / metabolism*
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Cadmium / pharmacology*
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Cell Division / drug effects
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Cysteine Proteinase Inhibitors / pharmacology
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Cysteine Synthase
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Dose-Response Relationship, Drug
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Drug Resistance, Fungal / genetics
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Hydrogen Sulfide / metabolism
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Immunoblotting
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Immunoprecipitation
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Leupeptins / pharmacology
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Multienzyme Complexes / genetics
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Multienzyme Complexes / metabolism
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Mutation
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Proteasome Endopeptidase Complex / metabolism
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Proteasome Inhibitors
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Saccharomyces cerevisiae / drug effects*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Ubiquitin / metabolism
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Ubiquitin-Conjugating Enzymes
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Ubiquitin-Protein Ligase Complexes / genetics
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Ubiquitin-Protein Ligase Complexes / metabolism*
Substances
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Basic-Leucine Zipper Transcription Factors
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Cysteine Proteinase Inhibitors
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Leupeptins
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MET4 protein, S cerevisiae
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Multienzyme Complexes
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Proteasome Inhibitors
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Saccharomyces cerevisiae Proteins
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Ubiquitin
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Cadmium
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CDC34 protein, S cerevisiae
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Ubiquitin-Conjugating Enzymes
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Ubiquitin-Protein Ligase Complexes
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Anaphase-Promoting Complex-Cyclosome
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Cysteine Synthase
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MET17 protein, S cerevisiae
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Proteasome Endopeptidase Complex
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benzyloxycarbonylleucyl-leucyl-leucine aldehyde
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Hydrogen Sulfide