A Nicotiana plumbaginifolia protein labeled with an azido cytokinin agonist is a glutathione S-transferase
A Nicotiana plumbaginifolia protein labeled with an azido cytokinin agonist is a glutathione S-transferase
复制标题
DOI：
10.1034/j.1399-3054.1998.1030114.x
复制
发表时间：
1998-05-01
影响因子：
6.4
通讯作者：
Laloue, M
中科院分区：
文献类型：
--
作者：
Gonneau, J;Mornet, R;Laloue, M
细胞分裂素的接收/转导机制仍然在很大程度上未知。我们用一种新的光亲和探针1-（2-叠氮基-6-氯吡啶-4-基）-3-（4-[H-3]）苯基脲（[H-3]azido-CPPU）寻找细胞分裂素结合蛋白。结合苯基脲型细胞分裂素的可溶性蛋白质已被特异性地光标记在烟草plumbaginifolia（cv. Viviani系pbH 1D）叶提取物。通过亲和层析将蛋白纯化至均一。其N-末端氨基酸序列以及四个内部肽序列与谷胱甘肽S-转移酶超家族（GST，EC 2.5.1.18）的θ类高度同源，包括鉴定为生长素结合蛋白的天仙子和拟南芥GST。纯化的N.白花丹蛋白还具有GST酶活性。为了测试这种GST的可能参与细胞分裂素的作用机制，我们研究了结合的tritiated-CPPU纯化的GST中存在的各种化合物，细胞分裂素激动剂，细胞分裂素拮抗剂，或无活性的分子。噻苯隆是一个很差的竞争者，玉米素和活性光学异构体R-MeBA都不能抑制CPPU的结合。细胞分裂素活性与所测试分子的结合特性之间没有相关性。我们的研究结果证实，植物GST结合不同的化合物，特别是植物激素，但可能没有特定的作用方式的细胞分裂素。
The mechanisms of reception/transduction of cytokinins still remain largely unknown. We used 1-(2-azido-6-chloropyrid-4-yl)-3-(4-[H-3])phenylurea ([H-3]azido-CPPU), a new photoaffinity probe to search For cytokinin-binding proteins. A soluble protein that binds phenylurea-type cytokinins has been specifically photolabeled in Nicotiana plumbaginifolia (cv. Viviani line pbH1D) leaf extracts. The protein was purified to homogeneity by affinity chromatography. Its N-terminal amino acid sequence, as well as four internal peptide sequences are highly homologous with the theta class of the glutathione S-transferase superfamily (GST, EC 2.5.1.18) including Hyoscyamus muticus and Arabidopsis GSTs identified as auxin-binding proteins. The purified N. plumbaginifolia protein also possesses GST enzymatic activity. To test the possible involvement of this GST in the mechanism of action of cytokinin, we studied the binding of tritiated-CPPU to the purified GST in the presence of various compounds, cytokinin agonists, cytokinin antagonists, or inactive molecules. Thidiazuron is a poor competitor, and neither zeatin nor the active optical isomer R-MeBA is able to inhibit the binding of CPPU. There is no correlation between the cytokinin activity and the binding properties of the molecules tested. Our results confirmed that plant GSTs bind different compounds, especially plant hormones but probably have no specific role in the mode of action of cytokinins.