Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kusunoki-cho 7-5-1, Chuo-ku, Kobe 650-0017, Japan.
Mol Genet Genomics. 2012 Aug;287(8):651-62. doi: 10.1007/s00438-012-0705-9. Epub 2012 Jul 18.
Cobalt is an essential micronutrient but is toxic when present in excess. To study cobalt homeostasis we performed a genome-wide screen for deletion strains that show sensitivity or resistance to CoCl(2). Among 54 cobalt-sensitive strains, 18 are supersensitive strains, which are involved in histidine biosynthetic process, ubiquitination, mitochondria function, membrane trafficking, transporter and a variety of other known functions or still unknown functions. Furthermore, we identified 56 cobalt-resistant deletion strains, which are mainly involved in mitochondria function, signal transduction, ubiquitination, and gene expression and chromatin remodeling. Notably, deletion of the zhf1(+) gene, encoding a zinc ion transporter, confers supersensitivity to cobalt and overexpression of the zhf1(+) gene confers marked tolerance to cobalt, indicating that Zhf1 play key roles in cobalt detoxification. Interestingly, all the histidine-auxotrophic mutants displayed cobalt sensitivity and deletion of cationic amino acid transporter Cat1, which was shown to be involved in histidine uptake, suppressed the CoCl(2)-sensitive growth defect of the his2 mutants, suggesting that CoCl(2) may be transported into the cell together with histidine via histidine transporters including Cat1. In addition, we obtained results suggesting that the E2 ubiquitin conjugating enzyme Rhp6 and Sty1 stress MAP kinase pathway are involved in the regulation of cobalt homeostasis. Altogether, our genome-wide study demonstrates for the first time the mechanisms of cobalt homeostasis, particularly its uptake and detoxification in fission yeast.
钴是一种必需的微量元素，但过量存在时会有毒性。为了研究钴的体内平衡，我们进行了全基因组筛选，以寻找对 CoCl₂表现出敏感性或抗性的缺失菌株。在 54 株钴敏感菌株中，有 18 株是超敏菌株，它们参与组氨酸生物合成过程、泛素化、线粒体功能、膜转运、转运体以及各种其他已知功能或仍未知功能。此外，我们还鉴定了 56 株钴抗性缺失菌株，它们主要参与线粒体功能、信号转导、泛素化以及基因表达和染色质重塑。值得注意的是，编码锌离子转运体的 zhf1(+)基因的缺失赋予了钴的超敏性，而 zhf1(+)基因的过表达赋予了钴的显著耐受性，表明 Zhf1 在钴解毒中发挥关键作用。有趣的是，所有组氨酸营养缺陷型突变体都表现出钴敏感性，并且阳离子氨基酸转运体 Cat1 的缺失，该基因被证明参与组氨酸摄取，抑制了 his2 突变体的 CoCl₂敏感生长缺陷，表明 CoCl₂可能与组氨酸一起通过包括 Cat1 在内的组氨酸转运体进入细胞。此外，我们获得的结果表明，E2 泛素连接酶 Rhp6 和 Sty1 应激 MAP 激酶途径参与了钴体内平衡的调节。总之，我们的全基因组研究首次展示了裂殖酵母钴体内平衡的机制，特别是其摄取和解毒。
