Nitrate and Phosphate Transporters Rescue Fluoride Toxicity in Yeast
Nitrate and Phosphate Transporters Rescue Fluoride Toxicity in Yeast
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DOI：
10.1021/acs.chemrestox.9b00315
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发表时间：
2019-11-01
影响因子：
4.1
通讯作者：
Strobel, Scott A.
中科院分区：
文献类型：
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作者：
Johnston, Nichole R.;Strobel, Scott A.
生物体暴露于空气、水和土壤中的氟化物。酵母和其他微生物利用氟化物通道作为防止细胞内氟化物积累和介导氟化物毒性的方法。因此，删除酿酒酵母中的氟化物输出基因（FEX）会导致氟化物敏感性增加 1000 倍以上。我们使用这种 FEX 敲除菌株来鉴定基因，这些基因在过度表达时能够部分缓解氟化物暴露的毒性。 SSU1、YHB1、IPP1、PHO87 和 PHO90 五个基因的过表达可将氟化物耐受性提高 2 至 10 倍。这些基因的过度表达并没有改善野生型酵母的氟化物抗性，这表明该机制是酵母中低氟化物毒性所特有的。 Ssu1p 和 Yhb1p 均在亚硝化应激反应中发挥作用，该反应是在氟化物暴露和金属流入时诱导的。 Ipp1p、Pho87p 和 Pho90p 增加细胞内正磷酸盐。通过在生长培养基中添加高浓度的磷酸盐，也可以部分减轻毒性。通过 RNA-Seq 监测的基因诱导证明，氟化物会抑制应激诱导时磷酸盐的输入，并导致营养缺乏和细胞器破坏。综合观察结果表明，跨膜营养转运蛋白是氟化物引起的应激期间最敏感的蛋白质之一。
Organisms are exposed to fluoride in the air, water, and soil. Yeast and other microbes utilize fluoride channels as a method to prevent intracellular fluoride accumulation and mediate fluoride toxicity. Consequently, deletion of fluoride exporter genes (FEX) in S. cerevisiae resulted in over 1000-fold increased fluoride sensitivity. We used this FEX knockout strain to identify genes, that when overexpressed, are able to partially relieve the toxicity of fluoride exposure. Overexpression of five genes, SSU1, YHB1, IPP1, PHO87, and PHO90, increase fluoride tolerance by 2- to 10-fold. Overexpression of these genes did not provide improved fluoride resistance in wild-type yeast, suggesting that the mechanism is specific to low fluoride toxicity in yeast. Ssu1p and Yhb1p both function in nitrosative stress response, which is induced upon fluoride exposure along with metal influx. Ipp1p, Pho87p, and Pho90p increase intracellular orthophosphate. toxicity is also partially mitigated by the addition of high levels of phosphate to the growth media. Fluoride inhibits phosphate import upon stress induction and causes nutrient starvation and organelle disruption, as supported by gene induction monitored through RNA-Seq. The combination of observations suggests that transmembrane nutrient transporters are among the most sensitized proteins during fluoride-instigated stress.