Teige Markus, Scheikl Elisabeth, Eulgem Thomas, Dóczi Róbert, Ichimura Kazuya, Shinozaki Kazuo, Dangl Jeffery L, Hirt Heribert
Max F. Perutz Laboratories, University of Vienna and Gregor Mendel Institute of Molecular Plant Sciences, Austrian Academy of Sciences, Vienna Biocenter, Dr. Bohrgasse 9, A-1030 Vienna, Austria.
Mol Cell. 2004 Jul 2;15(1):141-52. doi: 10.1016/j.molcel.2004.06.023.
The Arabidopsis mitogen-activated protein kinase (MAPK) kinase 2 (MKK2) and the downstream MAPKs MPK4 and MPK6 were isolated by functional complementation of osmosensitive yeast mutants. In Arabidopsis protoplasts, MKK2 was specifically activated by cold and salt stress and by the stress-induced MAPK kinase kinase MEKK1. Yeast two-hybrid, in vitro, and in vivo protein kinase assays revealed that MKK2 directly targets MPK4 and MPK6. Accordingly, plants overexpressing MKK2 exhibited constitutive MPK4 and MPK6 activity, constitutively upregulated expression of stress-induced marker genes, and increased freezing and salt tolerance. In contrast, mkk2 null plants were impaired in MPK4 and MPK6 activation and were hypersensitive to salt and cold stress. Full genome transcriptome analysis of MKK2-overexpressing plants demonstrated altered expression of 152 genes involved in transcriptional regulation, signal transduction, cellular defense, and stress metabolism. These data identify a MAP kinase signaling cascade mediating cold and salt stress tolerance in plants.
通过对渗透敏感型酵母突变体进行功能互补，分离出了拟南芥促分裂原活化蛋白激酶（MAPK）激酶2（MKK2）及其下游的MAPK MPK4和MPK6。在拟南芥原生质体中，MKK2被冷胁迫、盐胁迫以及胁迫诱导的MAPK激酶激酶MEKK1特异性激活。酵母双杂交、体外和体内蛋白激酶分析表明，MKK2直接作用于MPK4和MPK6。因此，过表达MKK2的植物表现出组成型的MPK4和MPK6活性，胁迫诱导型标记基因的表达组成型上调，并且抗冻性和耐盐性增强。相反，mkk2基因缺失的植物在MPK4和MPK6激活方面存在缺陷，对盐胁迫和冷胁迫高度敏感。对过表达MKK2的植物进行全基因组转录组分析表明，参与转录调控、信号转导、细胞防御和胁迫代谢的152个基因的表达发生了改变。这些数据确定了一条介导植物抗冷和耐盐胁迫的MAP激酶信号级联。
