Potassium resistance of halotolerant and alkaliphilic Halomonas sp. Y2 by a Na+-induced K+ extrusion mechanism
Potassium resistance of halotolerant and alkaliphilic Halomonas sp. Y2 by a Na+-induced K+ extrusion mechanism
复制标题
耐盐和嗜碱盐单胞菌的钾抗性。
DOI：
10.1099/mic.0.000784
复制
发表时间：
2019-04-01
期刊：
影响因子：
2.8
通讯作者：
Yang, Chunyu
中科院分区：
文献类型：
--
作者：
Meng, Yiwei;Lv, Peiwen;Yang, Chunyu
In most halophiles, K+ generally acts as a major osmotic solute for osmotic adjustment and pH homeostasis.然而，菌株也需要排出过量的细胞内K+以避免其毒性。 In the halotolerant and alkaliphilic Halomonas sp. Y2，当细胞面临高细胞外 K+ 压力和补充毫摩尔 Na+ 离子时，观察到 Na+ 诱导的 K+ 挤出过程。在菌株基因组中发现的三个机械敏感通道 (KefA) 和两个 K+/H+ 反向转运蛋白中，ke1 在 pH 8.0 时对离子应激表现出约 3-5 倍的上调，而在 pH 10.0 时观察到 Ha-mrp 的上调要高得多。 Compared to the growth of wild-type Halomonas sp. Y2, deletion of these genes from the strain resulted in different growth phenotypes in response to the osmotic pressure of potassium.结合这些基因的转录反应，我们提出Ke1的KefA通道是弱碱性下K+挤出过程的主要贡献者，而Mrp系统在缓解高pH下K+含量方面起着关键作用。 The combination of these strategies allows Halomonas sp. Y2 to grow over a range of extracellular pH and ion concentrations, and thus protect cells under high osmotic stress conditions.
In most halophiles, K+ generally acts as a major osmotic solute for osmotic adjustment and pH homeostasis. However, strains also need to extrude excessive intracellular K+ to avoid its toxicity. In the halotolerant and alkaliphilic Halomonas sp. Y2, an Na+-induced K+ extrusion process was observed when the cells were confronted with high extracellular K+ pressure and supplementation by millimolar Na+ ions. Among three mechanosensitive channels (KefA) and two K+/H+ antiporters founded in the genome of the strain, ke1 displayed around 3-5-fold upregulation to ion stress at pH 8.0, while much higher upregulation of Ha-mrp was observed at pH 10.0. Compared to the growth of wild-type Halomonas sp. Y2, deletion of these genes from the strain resulted in different growth phenotypes in response to the osmotic pressure of potassium. In combination with the transcriptional response of these genes, we proposed that the KefA channel of Ke1 is the main contributor to the K+-extrusion process under weak alkalinity, while the Mrp system plays critical roles in alleviating K+ contents at high pH. The combination of these strategies allows Halomonas sp. Y2 to grow over a range of extracellular pH and ion concentrations, and thus protect cells under high osmotic stress conditions.