Molecular Characteristics of the Conserved Aspergillus nidulans Transcription Factor Mac1 and Its Functions in Response to Copper Starvation
Molecular Characteristics of the Conserved Aspergillus nidulans Transcription Factor Mac1 and Its Functions in Response to Copper Starvation
复制标题
保守构巢曲霉转录因子Mac1的分子特征及其响应铜饥饿的功能
DOI：
10.1128/msphere.00670-18
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发表时间：
2019-01-01
期刊：
影响因子：
4.8
通讯作者：
Lu, Ling
中科院分区：
文献类型：
--
作者：
Cai, Zhendong;Du, Wenlong;Lu, Ling
铜是多种生化过程中酶的重要辅助因子。因此，铜的获取在细胞存活和增殖中起着至关重要的作用，特别是在铜饥饿期间。了解低铜响应转录因子 Mac1 感知铜的关键基序对于理解铜摄取的控制方式非常重要。这项研究的结果表明，Cu 拳头基序（而不是富含 Cys 的基序）对于曲霉中 Mac1 介导的 Cu 吸收至关重要。此外，构巢曲霉在铜饥饿期间，铜转运蛋白 CtrA2 和 CtrC 都是 Mac1 介导的铜吸收所必需的，这表明曲霉中存在物种特异性的铜获取机制。摘要 铜 (Cu) 是所有生物体必需的微量元素，饥饿期间获取铜对于细胞生存和增殖非常重要。尽管已在烟曲霉中鉴定出 Cu 饥饿反应转录因子 Mac1 及其靶向 Cu 转运蛋白，但 Mac1 介导的 Cu 获取的分子机制尚未在曲霉中进行研究。我们证明了 Mac1 及其调节的铜转运蛋白是构巢曲霉在铜饥饿期间生长和分生孢子梗发育所必需的。此外，构巢曲霉Mac1 (AnMac1)与烟曲霉同源物表现出高度功能保守性，但与酿酒酵母和粟酒裂殖酵母中的同源物不具有高度功能保守性。构巢曲霉中 Mac1 的分子表征表明，Mac1 介导的低 Cu 反应需要含有 Cys、RGHR 和 GRP 残基的“Cu 拳头”基序（即残基 1 至 40），但不需要富含 Cys 的基序 REP-I 和 REP-II。值得注意的是，单独过度表达 CtrA2 Cu 转运蛋白或 CtrC Cu 转运蛋白均无法在功能上挽救 AnMac1 缺失菌株中的缺陷，这意味着 Cu 摄取在 Cu 饥饿期间可能需要 CtrA2 和 CtrC，这与烟曲霉的结果不同。这项研究的结果进一步表明，烟曲霉和构巢曲霉中保守的 Mac1 介导的铜吸收机制也是物种特异性的。重要性 铜是多种生化过程中酶的重要辅助因子。因此，铜的获取在细胞存活和增殖中起着至关重要的作用，特别是在铜饥饿期间。了解低铜响应转录因子 Mac1 感知铜的关键基序对于理解铜摄取的控制方式非常重要。这项研究的结果表明，Cu 拳头基序（而不是富含 Cys 的基序）对于曲霉中 Mac1 介导的 Cu 吸收至关重要。此外，构巢曲霉在铜饥饿期间，铜转运蛋白 CtrA2 和 CtrC 都是 Mac1 介导的铜吸收所必需的，这表明曲霉中存在物种特异性的铜获取机制。
Copper is an essential cofactor of enzymes during a variety of biochemical processes. Therefore, Cu acquisition plays critical roles in cell survival and proliferation, especially during Cu starvation. Knowledge of the key motif(s) by which the low-Cu-responsive transcription factor Mac1 senses Cu is important for understanding how Cu uptake is controlled. Findings in this study demonstrated that the Cu fist motif, but not Cys-rich motifs, is essential for Mac1-mediated Cu uptake in Aspergillus. In addition, Cu transporters CtrA2 and CtrC are both required for Mac1-mediated Cu uptake during Cu starvation in A. nidulans, indicating that species-specific machinery exists for Cu acquisition in Aspergillus. ABSTRACT Copper (Cu) is an essential trace element in all organisms, and Cu acquisition during periods of starvation is important for cell survival and proliferation. Although the Cu starvation-responsive transcription factor Mac1 as well as its targeted Cu transporters have been identified in Aspergillus fumigatus, the molecular mechanisms of Mac1-mediated Cu acquisition have not yet been investigated in Aspergillus. We demonstrated that Mac1 and its regulated Cu transporters are required for growth and conidiophore development during Cu starvation in Aspergillus nidulans. Moreover, A. nidulans Mac1 (AnMac1) showed highly functional conservation with the A. fumigatus homolog but not with homologs in Saccharomyces cerevisiae and Schizosaccharomyces pombe. Molecular characterization of Mac1 in A. nidulans demonstrated that the “Cu fist” motif (i.e., residues 1 through 40) harboring Cys, RGHR, and GRP residues is required for the Mac1-mediated low-Cu response but not the Cys-rich motifs REP-I and REP-II. Notably, overexpression of either the CtrA2 Cu transporter or the CtrC Cu transporter individually was unable to functionally rescue the defects in the AnMac1 deletion strain, implying that Cu uptake might require both CtrA2 and CtrC during Cu starvation, which is different from results seen with A. fumigatus. Findings in this study further suggest that the conserved Mac1-mediated Cu uptake machinery in A. fumigatus and A. nidulans is also species specific. IMPORTANCE Copper is an essential cofactor of enzymes during a variety of biochemical processes. Therefore, Cu acquisition plays critical roles in cell survival and proliferation, especially during Cu starvation. Knowledge of the key motif(s) by which the low-Cu-responsive transcription factor Mac1 senses Cu is important for understanding how Cu uptake is controlled. Findings in this study demonstrated that the Cu fist motif, but not Cys-rich motifs, is essential for Mac1-mediated Cu uptake in Aspergillus. In addition, Cu transporters CtrA2 and CtrC are both required for Mac1-mediated Cu uptake during Cu starvation in A. nidulans, indicating that species-specific machinery exists for Cu acquisition in Aspergillus.