Disruption of the Saccharomyces cerevisiae cell-wall pathway gene SLG1 causes hypersensitivity to the antitumor drug bleomycin
Disruption of the Saccharomyces cerevisiae cell-wall pathway gene SLG1 causes hypersensitivity to the antitumor drug bleomycin
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DOI：
10.1007/s00438-003-0812-8
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发表时间：
2003-04-01
影响因子：
3.1
通讯作者：
Ramotar, D
中科院分区：
文献类型：
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作者：
Leduc, A;He, CH;Ramotar, D
博来霉素是一种抗肿瘤药物，通过自由基依赖性机制损伤 DNA，DNA 修复缺陷的酵母突变体对该药物过敏。为了确定酵母中可能导致博来霉素抗性的可能途径，我们对一组博莱霉素敏感突变体进行了表征，这些突变体之前使用转座子 miniTn3::Leu2::LacZ::AMP(R) 通过插入诱变分离。其中一个突变体在 SLG1 基因中包含一个单插入片段，该基因编码一种可感知细胞壁应激的细胞膜蛋白，并通过激活蛋白激酶 C 信号通路来维持细胞壁功能。亲本菌株中 SLG1 基因的缺失会导致对博莱霉素过敏，这与受损 DNA 的积累有关。表达天然 SLG1 基因或增加 PKC1 基因剂量的质粒恢复了 slg1Delta 突变体的博莱霉素抗性。二维凝胶电泳显示，接触博来霉素会触发某些蛋白质的表达，可能是为了以 Slg1 依赖性方式维持细胞壁功能。此外，缺乏细胞壁功能的突变体被发现对博莱霉素过敏。我们得出的结论是，缺乏维持细胞壁功能的蛋白质的突变体限制博莱霉素进入细胞的能力受到严重损害。因此，这些突变体在暴露于培养基中的博莱霉素时会增加遗传毒性。我们的结果表明，DNA 修复以外的主要机制正在酵母中发挥作用，介导博莱霉素抗性。
Bleomycin is an antitumor drug that damages DNA via a free radical-dependent mechanism, and yeast mutants defective in DNA repair are hypersensitive to the drug. To identify possible pathways that may contribute to bleomycin resistance in yeast, we characterized a panel of bleomycin-sensitive mutants that were previously isolated by insertion mutagenesis using the transposon miniTn3::Leu2::LacZ::AMP(R). One of these mutants harbored a single insertion in the SLG1 gene, which encodes a cell membrane protein that senses cell wall stress, and functions to maintain cell wall function by activating the protein kinase C signaling pathway. Deletion of the SLG1 gene in parental strains caused hypersensitivity to bleomycin, and this correlated with an accumulation of damaged DNA. A plasmid that expresses the native SLG1 gene or that increases PKC1 gene dosage restored bleomycin resistance to the slg1Delta mutant. Two-dimensional gel electrophoresis revealed that exposure to bleomycin triggered the expression of certain proteins, presumably to maintain cell wall function, in a Slg1-dependent manner. In addition, mutants lacking cell wall function were found to be hypersensitive to bleomycin. We conclude that mutants deficient in proteins that maintain cell wall function are severely compromised in their ability to limit bleomycin entry into the cell. Therefore, these mutants are burdened with increased genotoxicity upon exposure to bleomycin in the medium. Our results show that major mechanisms other than DNA repair are operating in yeast to mediate bleomycin resistance.