Choi Seo-Wha, Lee Seul-Bee, Na Yeon-Ju, Jeung Sun-Geum, Kim Soo Young
Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Korea.
Mol Cells. 2017 Mar;40(3):230-242. doi: 10.14348/molcells.2017.0002. Epub 2017 Mar 14.
In the Arabidopsis genome, approximately 80 MAP3Ks (mitogen-activated protein kinase kinase kinases) have been identified. However, only a few of them have been characterized, and the functions of most MAP3Ks are largely unknown. In this paper, we report the function of MAP3K16 and several other MAP3Ks, MAP3K14/15/17/18, whose expression is salt-inducible. We prepared overexpression (OX) lines and analyzed their phenotypes. The result showed that the transgenic plants were ABA-insensitive during seed germination and cotyledon greening stage but their root growth was ABA-hypersensitive. The OX lines were more susceptible to water-deficit condition at later growth stage in soil. A knockout (KO) line, on the other hand, exhibited opposite phenotypes. In similar transgenic analyses, we found that OX and KO lines displayed similar phenotypes to those of MA3K16, suggesting the functional redundancy among them. MAP3K16 possesses kinase activity, and we carried out two-hybrid analyses to identify MAP3K16 substrates. Our results indicate that MAP3K16 interacts with MKK3 and the negative regulator of ABA response, ABR1, in yeast. Furthermore, MAP3K16 recombinant protein could phosphorylate MKK3 and ABR1, suggesting that they might be MAP3K16 substrates. Collectively, our results demonstrate that MAP3K16 and MAP3K14/15/17/18 are involved in ABA response, playing negative or positive roles depending on developmental stage and that MAP3K16 may function MKK3 and ABR1.
在拟南芥基因组中，已鉴定出约80种促分裂原活化蛋白激酶激酶激酶（MAP3K）。然而，其中只有少数已被表征，大多数MAP3K的功能在很大程度上尚不清楚。在本文中，我们报道了MAP3K16以及其他几种MAP3K，即MAP3K14/15/17/18的功能，它们的表达受盐诱导。我们制备了过表达（OX）系并分析了它们的表型。结果表明，转基因植物在种子萌发和子叶绿化阶段对脱落酸（ABA）不敏感，但它们的根生长对ABA超敏感 O X系在土壤中生长后期对缺水条件更敏感。另一方面，一个敲除（KO）系表现出相反的表型。在类似的转基因分析中，我们发现OX和KO系表现出与MAP3K16相似的表型，表明它们之间存在功能冗余。MAP3K16具有激酶活性，我们进行了双杂交分析以鉴定MAP3K16的底物。我们的结果表明，在酵母中，MAP3K16与MKK3以及ABA反应的负调节因子ABR1相互作用。此外，MAP3K16重组蛋白可以磷酸化MKK3和ABR1，表明它们可能是MAP3K16的底物。总的来说，我们的结果表明，MAP3K16和MAP3K14/15/17/18参与ABA反应，根据发育阶段发挥负或正作用，并且MAP3K16可能作用于MKK3和ABR1。
