Cation/proton antiporters play a major role in the control of cytosolic ion concentrations in prokaryotes and eukaryotes organisms. In yeast, we previously demonstrated that Vnx1p is a vacuolar monovalent cation/H+ exchanger showing Na+ /H+ and K+ /H+ antiporter activity. We have also shown that disruption of VNX1 results in an almost complete abolishment of vacuolar Na+ /H+ exchange, but yeast cells overexpressing the complete protein do not show improved salinity tolerance. In this study, we have identified an autoinhibitory N-terminal domain and have engineered a constitutively activated version of Vnx1p, by removing this domain. Contrary to the wild type protein, the activated protein has a pronounced effect on yeast salt tolerance and vacuolar pH. Expression of this truncated VNX1 gene also improves Arabidopsis salt tolerance and increases Na+ and K+ accumulation of salt grown plants thus suggesting a biotechnological potential of activated Vnx1p to improve salt tolerance of crop plants.

中文翻译：

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酵母液泡（Na +，K +）/ H +反向转运蛋白Vnx1p的N末端结构域的缺失提高了酵母和转基因拟南芥中的耐盐性。

阳离子/质子反转运蛋白在原核生物和真核生物中的胞质离子浓度控制中起主要作用。在酵母中，我们先前证明Vnx1p是液泡单价阳离子/ H +交换剂，显示Na + / H +和K + / H +反转运蛋白活性。我们还显示，破坏VNX1会导致液泡Na + / H +交换几乎完全被取消，但是过表达完整蛋白的酵母细胞却没有显示出更高的盐度耐受性。在这项研究中，我们确定了一个自抑制性N末端结构域，并通过去除该结构域设计了Vnx1p的组成型激活形式。与野生型蛋白质相反，活化的蛋白质对酵母盐耐受性和液泡pH具有显着影响。