Overexpression of the ubiquitin-conjugating enzyme Cdc34 confers resistance to methylmercury in Saccharomyces cerevisiae
Overexpression of the ubiquitin-conjugating enzyme Cdc34 confers resistance to methylmercury in Saccharomyces cerevisiae
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DOI：
10.1124/mol.61.4.738
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发表时间：
2002-04-01
影响因子：
3.6
通讯作者：
Naganuma, A
中科院分区：
文献类型：
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作者：
Furuchi, T;Hwang, GW;Naganuma, A
使用来自酿酒酵母的基因组DNA文库，在酵母中搜索赋予甲基汞抗性的基因。将基因组文库引入酵母中，并选择在正常毒性浓度的甲基汞存在下生长的转化体。我们对来自对甲基汞具有最高抗性的克隆的质粒中的基因组DNA片段进行测序，并分析该序列是否存在可能赋予甲基汞抗性的开放阅读框。我们发现了一个基因，CDC34（也称为UBC 3），当在酵母中过度表达时，它会增加对甲基汞的抗性。CDC34编码一种泛素结合酶，这种蛋白质在选择性靶向降解蛋白质方面发挥重要作用。另外两个泛素结合酶基因UBC4和UBC7的过表达也赋予了对甲基汞的抗性。用CDC34基因转化的酵母菌株不仅对甲基汞有抗性，而且对氯化汞和对氯汞苯甲酸盐也有抗性。据我们所知，这是第一次证明，过表达的基因的泛素结合酶赋予抵抗外源性。我们的研究结果表明，泛素化系统可能参与保护对汞化合物的毒性，如甲基汞，在真核细胞。
A search was made for genes that confer resistance to methylmercury in yeast using a genomic DNA library derived from Saccharomyces cerevisiae. The genomic library was introduced into yeast and transformants that grew in the presence of a normally toxic concentration of methylmercury were selected. We sequenced the genomic DNA fragment in the plasmid from the clone with the highest resistance to methylmercury and analyzed the sequence for presence of an open reading frame that might confer resistance to methylmercury. We identified a gene, CDC34 (also known as UBC3), that increased resistance to methylmercury when overexpressed in yeast. CDC34 encodes a ubiquitin-conjugating enzyme; such proteins play important roles in the selective targeting of proteins for degradation. Overexpression of UBC4 and of UBC7, two other genes for ubiquitin-conjugating enzymes, also conferred resistance to methylmercury. Yeast strains transformed with the CDC34 gene were resistant not only to methylmercury but also to mercuric chloride and p-chloromercuribenzoate. To our knowledge, this is the first demonstration that overexpression of genes for ubiquitin-conjugating enzymes confers resistance to xenobiotics. Our results suggest that ubiquitination system might be involved in protection against the toxicity of mercury compounds, such as methylmercury, in eukaryotic cells.