Both the extracellular leucine-rich repeat domain and the kinase activity of FLS2 are required for flagellin binding and signaling in arabidopsis
Both the extracellular leucine-rich repeat domain and the kinase activity of FLS2 are required for flagellin binding and signaling in arabidopsis
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DOI：
10.1105/tpc.13.5.1155
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发表时间：
2001-05-01
期刊：
影响因子：
11.6
通讯作者：
Boller, T
中科院分区：
文献类型：
--
作者：
Gómez-Gómez, L;Bauer, Z;Boller, T
在拟南芥中，鞭毛蛋白防御反应的激活是通过对鞭毛蛋白最保守的结构域（以肽 flg22 为代表）的特异性识别来触发的，在涉及 FLS2 基因的过程中，FLS2 基因编码富含亮氨酸的重复丝氨酸/苏氨酸蛋白激酶。我们在此发现两个 fls2 突变等位基因 fls2-24 和 fls2-17，之前已显示它们对 flg22 不敏感，也会导致鞭毛蛋白结合受损。当功能性 FLS2 基因在每个 fls2 突变体植物中作为转基因表达时，这些特征得以恢复，表明 FLS2 对于鞭毛蛋白结合是必需的。 fls2-17的点突变；等位基因位于激酶结构域。携带这种错义突变的激酶在大肠杆菌中表达时缺乏自磷酸化活性，这表明结合需要激酶活性，并且可能影响鞭毛蛋白受体复合物的稳定性。我们进一步表明，拟南芥中激酶相关蛋白磷酸酶 (KAPP) 的过度表达会导致植物对鞭毛蛋白处理不敏感，并且我们显示这些植物中 flg22 的结合减少。此外，使用酵母双杂交系统，我们展示了 KAPP 与 FLS2 激酶结构域的物理相互作用。这些结果表明 KAPP 作为 FLS2 信号转导途径的负调节因子发挥作用，并且 FLS2 的磷酸化对于鞭毛蛋白受体复合物的正确结合和信号传导是必需的。
In Arabidopsis, activation of defense responses by flagellin is triggered by the specific recognition of the most conserved domain of flagellin, represented by the peptide flg22, in a process involving the FLS2 gene, which encodes a leucine-rich repeat serine/threonine protein kinase, We shaw here that the two fls2 mutant alleles, fls2-24 and fls2-17, which were shown previously to confer insensitivity to flg22, also cause impaired flagellin binding. These features are rescued when a functional FLS2 gene is expressed as a transgene in each of the fls2 mutant plants, indicating that FLS2 is necessary for flagellin binding. The point mutation of the fls2-17; allele lies in the kinase domain. A kinase carrying this missense mutation lacked autophosphorylation activity when expressed in Escherichia coli, This indicates that kinase activity is required for binding and probably affects the stability of the flagellin receptor complex. We further show that overexpression of the kinase-associated protein phosphatase (KAPP) in Arabidopsis results in plants that are insensitive to flagellin treatment, and we show reduced flg22 binding in these plants. Furthermore, using the yeast two-hybrid system, we show physical interaction of KAPP with the kinase domain of FLS2. These results suggest that KAPP functions as a negative regulator of the FLS2 signal transduction pathway and that the phosphorylation of FLS2 is necessary for proper binding and signaling of the flagellin receptor complex.