Eukaryotic resistance to fluoride toxicity mediated by a widespread family of fluoride export proteins
Eukaryotic resistance to fluoride toxicity mediated by a widespread family of fluoride export proteins
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DOI：
10.1073/pnas.1310439110
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发表时间：
2013-11-19
影响因子：
11.1
通讯作者：
Strobel, Scott A.
中科院分区：
文献类型：
--
作者：
Li, Sanshu;Smith, Kathryn D.;Strobel, Scott A.
氟是一种丰富的元素，对从细菌到人类的生物体都有毒性，但真核生物抵抗氟化物毒性的机制尚不清楚。大肠杆菌基因crcB最近被证明是受氟响应核糖开关，暗示它在氟的反应。在生命的所有领域中有超过8，000个crcB同源物，表明它在生物学中具有重要作用。在这里，我们证明了真核同源物[更名为FEX（氟化物输出）]功能的氟化物输出。在三种真核模式生物，粗糙脉孢菌、酿酒酵母和白色念珠菌中，FEX科斯对氟化物高度敏感（>200倍），但对其他卤化物不敏感。这些KO菌株中的一些不能在自来水中发现的氟化物浓度中生长。使用氟化物的放射性同位素F-18，我们开发了一种测定细胞内氟化物浓度的方法，并表明FEX缺失菌株积累的氟化物超过外部浓度，提供了FEX在氟化物流出中的功能的直接证据。此外，它们在氟化物存在下对较低的pH值更敏感。这些结果表明，真核FEX基因编码一种以前未被认识到的氟化物出口商在标准环境条件下生存所必需的。
Fluorine is an abundant element and is toxic to organisms from bacteria to humans, but the mechanisms by which eukaryotes resist fluoride toxicity are unknown. The Escherichia coli gene crcB was recently shown to be regulated by a fluoride-responsive riboswitch, implicating it in fluoride response. There are >8,000 crcB homologs across all domains of life, indicating that it has an important role in biology. Here we demonstrate that eukaryotic homologs [renamed FEX (fluoride exporter)] function in fluoride export. FEX KOs in three eukaryotic model organisms, Neurospora crassa, Saccharomyces cerevisiae, and Candida albicans, are highly sensitized to fluoride (>200-fold) but not to other halides. Some of these KO strains are unable to grow in fluoride concentrations found in tap water. Using the radioactive isotope of fluoride, F-18, we developed an assay to measure the intracellular fluoride concentration and show that the FEX deletion strains accumulate fluoride in excess of the external concentration, providing direct evidence of FEX function in fluoride efflux. In addition, they are more sensitive to lower pH in the presence of fluoride. These results demonstrate that eukaryotic FEX genes encode a previously unrecognized class of fluoride exporter necessary for survival in standard environmental conditions.