拟南芥AtJ3通过核质转运调控植物质膜H^+-ATPase活性与ABA响应

Trafficking of AtJ3 from the Nucleus to the Cytoplasm Regulates Plasma Membrane H^+-ATPase Activity and ABA Response in Arabidopsis

拟南芥AtJ3(Arabidopsis thaliana Dna J homolog 3)为一蛋白分子伴侣,在植物体内可通过与PKS5(SOS2-like protein kinase 5)蛋白激酶形成复合物来抑制PKS5的活性;同时AtJ3-PKS5复合物可对质膜上H^+-ATPase质子转运活性进行正向调节,并参与对外源ABA的响应。为揭示AtJ3-PKS5复合物参与质膜H^+-ATPase活性调节及对外源ABA响应中的作用,本研究以拟南芥AtJ3、PKS5不同突变体为材料,在盐及ABA共同处理下对AtJ3-PKS5复合物的功能及作用机制进行了探讨。结果显示,在2种因素共同处理下,AtJ3-PKS5复合物可同时对处理因素进行响应。即AtJ3-PKS5复合物可对质膜上H^+-ATPase质子转运活性进行调节,并使细胞内p H值发生变化,同时还可诱导ABI5下游ABA响应基因的表达;外源ABA可引起AtJ3从细胞核向细胞质的转运,从而增强了AtJ3对H^+-ATPase活性的调节。说明AtJ3-PKS5复合物在对H^+-ATPase活性调节及对外源ABA响应的交互代谢途径中起着关键调节子的作用。

Arabidopsis thaliana Dna J homolog 3（ AtJ3）,an Arabidopsis chaperone,interacts with SOS2-like protein kinase 5（ PKS5） to form the AtJ3-PKS5 complex and achieves its function through repressing activity of PKS5 in vivo. Moreover, the AtJ3-PKS5 complex positively regulates plasma membrane H-＋-ATPase activity and is involved in exogenous ABA response in Arabidopsis. In this study,salt- and ABA-treated Arabidopsis AtJ3 and PKS5 mutants were explored to elucidate the function and mechanism of the AtJ3-PKS5 complex in the simultaneous regulation of membrane H-＋-ATPase activity and ABA response. Results showed that the AtJ3-PKS5 complex not only led to changes in the cytosolic p H value via regulation of plasma membrane H-＋-ATPase activity,but also activated expression of the ABArelated responsive genes under the two treatments. Additionally,exogenous application of ABA induced trafficking of AtJ3 from the nucleus to the cytoplasm to enhance H-＋-ATPase activity,indicating that the AtJ3-PKS5 complex functions in ABA-meditated p H homeostasis.Taken together,our results suggest that the AtJ 3-PKS5 complex might serve as a key regulator in a crosstalk metabolic pathway of H-＋-ATPase activity regulation and exogenous ABA response.