Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Plant J. 2012 May;70(4):599-613. doi: 10.1111/j.1365-313X.2012.04901.x. Epub 2012 Feb 14.
Membrane-anchored receptor-like protein kinases (RLKs) recognize extracellular signals at the cell surface and activate the downstream signaling pathway by phosphorylating specific target proteins. We analyzed a receptor-like cytosolic kinase (RLCK) gene, ARCK1, whose expression was induced by abiotic stress. ARCK1 belongs to the cysteine-rich repeat (CRR) RLK sub-family and encodes a cytosolic protein kinase. The arck1 mutant showed higher sensitivity than the wild-type to ABA and osmotic stress during the post-germinative growth phase. CRK36, an abiotic stress-inducible RLK belonging to the CRR RLK sub-family, was screened as a potential interacting factor with ARCK1 by co-expression analyses and a yeast two-hybrid system. CRK36 physically interacted with ARCK1 in plant cells, and the kinase domain of CRK36 phosphorylated ARCK1 in vitro. We generated CRK36 RNAi transgenic plants, and found that transgenic plants with suppressed CRK36 expression showed higher sensitivity than arck1-2 to ABA and osmotic stress during the post-germinative growth phase. Microarray analysis using CRK36 RNAi plants revealed that suppression of CRK36 up-regulates several ABA-responsive genes, such as LEA genes, oleosin, ABI4 and ABI5. These results suggest that CRK36 and ARCK1 form a complex and negatively control ABA and osmotic stress signal transduction.
质膜锚定受体样蛋白激酶（RLKs）在细胞表面识别细胞外信号，并通过磷酸化特定的靶蛋白来激活下游信号通路。我们分析了一个受体样胞质激酶（RLCK）基因 ARCK1，其表达受非生物胁迫诱导。ARCK1 属于富含半胱氨酸重复（CRR）RLK 亚家族，编码胞质蛋白激酶。arck1 突变体在萌发后生长阶段对 ABA 和渗透胁迫的敏感性高于野生型。CRK36 是一个属于 CRR RLK 亚家族的非生物胁迫诱导 RLK，通过共表达分析和酵母双杂交系统筛选为与 ARCK1 潜在相互作用的因子。CRK36 在植物细胞中与 ARCK1 物理相互作用，并且 CRK36 的激酶结构域在体外磷酸化 ARCK1。我们生成了 CRK36 RNAi 转基因植物，并发现抑制 CRK36 表达的转基因植物在萌发后生长阶段对 ABA 和渗透胁迫的敏感性高于 arck1-2。使用 CRK36 RNAi 植物的微阵列分析显示，抑制 CRK36 会上调几个 ABA 反应基因，如 LEA 基因、油质体蛋白、ABI4 和 ABI5。这些结果表明，CRK36 和 ARCK1 形成一个复合物，并负调控 ABA 和渗透胁迫信号转导。
