蛋白磷酸酶ABI2调节SOS1蛋白的耐盐性

Salt Tolerance of SOS1 Protein Regulated by Protein Phosphatase ABI2

为研究盐生植物海马齿细胞膜Na+/H+逆转运蛋白SpSOS1的活性调节作用,本研究采用PCR的方法分别从海马齿和模式植物拟南芥中克隆到一个蛋白激酶基因SpCIPK8和一个蛋白磷酸酶基因AtABI2,在酵母异源表达系统中研究它们对海马齿细胞膜Na+/H+逆转运蛋白SpSOS1的活性调控。结果表明,蛋白激酶SpCIPK8的C-末端缺失形成的超活性突变体SpCIPK8-306可以正调节SpSOS1的活性,增强转基因酵母的耐盐性,在150 mmol/L Na Cl条件下生长,而再转入蛋白磷酸酶基因AtABI2后的酵母只能在75 mmol/L NaCl条件下生长。通过测定转基因酵母的离子含量,发现转SpCIPK8-306和SpSOS1的酵母中的Na+含量要显著低于转SpCIPK8-306、AtABI2、SpSOS1三个基因的酵母。本研究结果表明,蛋白激酶SpCIPK8可以正调控SpSOS1的活性,而蛋白磷酸酶At ABI2可能参与去磷酸化调节途径,降低蛋白的活性。本研究可为下一步深入研究海马齿体内的去磷酸化途径提供指导,对于研究生物体内的蛋白质活性调节具有重要意义。

In order to study the activity regulation of the plasma membrane Na+/H+antiporter SpSOS1 from the halophyte Sesuvium portulacastrum L.The kinase SpCIPK8 and the protein phosphatase AtABI2 were isolated from the halophyte Sesuvium portulacastrum L.and Arabidopsis thaliana using polymerase chain reaction(PCR)method.The function of Sp CIPK8 and AtABI2 to SpSOS1 were studied by the yeast heterologous expressing system.The results showed that the salt tolerance of the yeast strain co-transformed with the SpCIPK8-306 mutant only remaining kinase domain other than SpCIPK8 and SpSOS1 gene increased significantly,which could grow well under 150 mmol/L Na Cl.However,the yeast cells co-expression with SpCIPK8-306,AtABI2 and SpSOS1 only survived when treated with 75 mmol/L Na Cl.The Na+content in the yeast cells co-expressing SpSOS1 and SpCIPK8-306 was significantly lower than that transformed with three genes.These results indicated that SpCIPK8 could positively regulated the activity of SpSOS1,but the protein phosphatase AtABI2 might participate in the dephosphorylation network and negatively regulate protein activity.This paper would give theoretical guidance for futher study of dephosphorylation pathway of S.portulacastrum and have important significance for studying protein activity regulation in plant cells.