烟草幼苗两种钙调素结合蛋白激酶的活性调节及基因表达

在体外条件下,烟草两种钙调素结合蛋白激酶(NtCBK1与NtCBK2)自磷酸化活性的最适pH分别是7.5和8;Mg2 离子浓度对两种激酶自磷酸化活性影响比Na 离子大.Northern杂交结果显示:两基因在花和叶中都有大量表达,但在根和茎中NtCBKl的表达量明显多于NtCBK2;高盐处理会引起NtCBKl基因表达量升高,而高温、低温和干旱处理对该基因表达没有影响,说明NtCBKl参与植物体内盐诱导的信号转导.

Gene Expression and Activity Regulation of Two Calmodulin Binding Protein Kinases in Tobacco Seedling

Two differentc almodulin-binding proteinkinase cDNAs (NtCBK1/2) have been isolatedfrom tobacco. To understand the CBK protein ac-tivity regulation, we compared the activity regula-tion of NtCBK1 and NtCBK2 by pH, Mg2+ con-centration and Na+ concentration. We found theautophosphorylation of NtCBK1/2 reached themaximum in pH 7.5 and 8 respectively (Figs.1A and2A); Mg2+ and Na+ shown different effects on theactivity of NtCBKs, high and low Mg2+ concentra-tions both inhibited the activity of NtCBKs, but Na+had little effect on the kinase activity (Figs.1 and 2).In addition, to obtain further insight about the physi-ological roles of individual NtCBKs, we detectedthe expression profiles of CBKs. The results revealeddifferent patterns of expression of NtCBK1 andNtCBK2. Both are largely expressed in leaf and flower; but in stem and root, NtCBK1 gene hadstronger expression than NtCBK2 (Fig.3). NtCBK2expression was induced by GA treatment, whileNtCBK1 expression remainedu nchanged under GAtreatment (Fig.4B). Expression of both NtCBK1 andNtCBK2 increased in response to salt stress, theformer to a greater extent, and both expressions didnot change under high/low temperature, drought,NAA and ABA treatments (Fig.4).