Ullah Asad, Dutta Debajyoti, Fliegel Larry
Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada.
Department of Biotechnology, Thapar Institute of Engineering and Technology, Patiala 147004, Punjab, India.
Int J Mol Sci. 2025 Apr 9;26(8):3518. doi: 10.3390/ijms26083518.
SOS1 is a Na/H antiporter found in the plant membrane of and serves as a major transporter that extrudes Na across the plasma membrane of cells in exchange for intracellular H. The first 450 amino acids comprise the membrane transport domain. Using a yeast heterologous expression system, we examined nine different mutations that may either change specificity or improve salt tolerance. E261K had minor negative effects on the ability to confer tolerance to LiCl and NaCl. Mutation A399V had minor effects, lowering LiCl tolerance and slightly improving NaCl tolerance, as did the double mutant E261KA399V. Four different mutations of amino acid Y346 had varying effects. The Y346R mutation resulted in a major improvement in LiCl tolerance but did not affect NaCl tolerance. The L375I mutant showed impaired NaCl tolerance, whereas the Q362L mutant exhibited minor effects on salt tolerance. Our results demonstrate that amino acid Y346 is critical in ion selectivity and its mutation can dramatically improve LiCl salt tolerance. Other mutations showed minor improvements in the ability to confer NaCl tolerance (Y346F, A399V, and Y346A), leaving open the possibility that such mutations might improve salt tolerance in intact plant species.
SOS1是一种存在于植物细胞膜中的钠/氢反向转运蛋白，是一种主要的转运蛋白，可将钠离子排出细胞的质膜，以交换细胞内的氢离子。前450个氨基酸构成膜转运结构域。我们使用酵母异源表达系统，研究了9种可能改变特异性或提高耐盐性的不同突变。E261K对赋予对LiCl和NaCl耐受性的能力有轻微负面影响。A399V突变影响较小，降低了对LiCl的耐受性并略微提高了对NaCl的耐受性，双突变体E261KA399V也是如此。氨基酸Y346的四种不同突变有不同影响。Y346R突变导致对LiCl的耐受性大幅提高，但不影响对NaCl的耐受性。L375I突变体表现出对NaCl耐受性受损，而Q362L突变体对耐盐性影响较小。我们的结果表明，氨基酸Y346在离子选择性中起关键作用，其突变可显著提高对LiCl的耐盐性。其他突变在赋予对NaCl耐受性的能力方面有轻微改善（Y346F、A399V和Y346A），这使得这些突变可能提高完整植物物种耐盐性成为可能。
