香蕉MaNHX5关键耐盐氨基酸位点的鉴定及验证

为提高香蕉NHX基因的耐盐性，从巴西蕉(Musa acuminata L. AAA group)中克隆到一个MaNHXs基因家族的MaNHX5基因，利用生物信息学方法预测了Ma NHX5关键耐盐氨基酸位点和突变前后蛋白质结构的变化，通过定点突变技术将Ma NHX5蛋白的276位丝氨酸(S)成功突变为天冬氨酸(D)，利用AXT3盐敏感突变酵母进行功能回补试验。结果表明，将突变后的MaNHX5基因转入AXT3盐敏感突变酵母，200 mmol/L NaCl处理下，突变酵母耐盐性显著提高。由此推测Ma NHX5蛋白的Ser276对香蕉Na+跨液泡膜运输起重要作用。

Identification and verification of key salt-tolerant amino acid sites of banana MaNHX5

In order to improve the salt tolerance of banana NHX genes, we cloned a MaNHX5 gene from Musa acuminata L. AAA group and predicted the key salt-tolerant amino acid sites and mutant protein structure changes of MaNHX5 by using bioinformatics tools. The 276-position serine (S) of MaNHX5 protein was successfully mutated to aspartic acid (D) by site-directed mutagenesis, and the AXT3 salt-sensitive mutant yeast was used for a functional complementation test. The results showed that after the mutated MaNHX5 gene was transferred to AXT3 salt-sensitive mutant yeast, the salt tolerance of the mutant yeast was significantly improved under 200 mmol/L NaCl treatment. It is hypothesized that Ser276 of MaNHX5 protein plays an important role in the transport of Na⁺ across the tonoplast.