A receptor-like cytoplasmic kinase, BIK1, associates with a flagellin receptor complex to initiate plant innate immunity
A receptor-like cytoplasmic kinase, BIK1, associates with a flagellin receptor complex to initiate plant innate immunity
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DOI：
10.1073/pnas.0909705107
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发表时间：
2010-01-05
影响因子：
11.1
通讯作者：
He, Ping
中科院分区：
文献类型：
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作者：
Lu, Dongping;Wu, Shujing;He, Ping
植物和动物依靠先天免疫通过模式识别受体（PRR）检测微生物相关分子模式（MAMP）来预防感染。植物PRR FLS 2是一种富含亮氨酸的重复受体激酶，它识别细菌鞭毛蛋白，并通过与另一种富含亮氨酸的重复受体样激酶BAK 1结合来启动免疫信号传导。FLS 2/BAK 1受体复合物如何激活细胞内信号级联仍然是未知的。在这里，我们确定了受体样细胞质激酶BIK 1，这是迅速磷酸化后鞭毛感知，这取决于FLS 2和BAK 1。BIK 1在体内和体外与FLS 2和BAK 1结合。BIK 1被BAK 1磷酸化，BIK 1也在体外直接磷酸化BAK 1和FLS 2。BIK 1的鞭毛蛋白磷酸化位点Thr（237）是其在BAK 1和FLS 2上的磷酸化所必需的，这表明BIK 1可能在鞭毛蛋白感知后首先磷酸化，随后转磷酸化FLS 2/BAK 1以传播鞭毛蛋白信号传导。重要的是，bik 1突变体在多种鞭毛蛋白介导的反应和对非致病性细菌感染的免疫中受到损害。因此，BIK 1是MAMP信号转导中的重要组分，其将MAMP受体复合物与下游细胞内信号传导连接。
Plants and animals rely on innate immunity to prevent infections by detection of microbe-associated molecular patterns (MAMPs) through pattern-recognition receptors (PRRs). The plant PRR FLS2, a leucine-rich repeat-receptor kinase, recognizes bacterial flagellin and initiates immune signaling by association with another leucine-rich repeat-receptor-like kinase, BAK1. It remains unknown how the FLS2/BAK1 receptor complex activates intracellular signaling cascades. Here we identified the receptor-like cytoplasmic kinase BIK1 that is rapidly phosphorylated upon flagellin perception, depending on both FLS2 and BAK1. BIK1 associates with FLS2 and BAK1 in vivo and in vitro. BIK1 is phosphorylated by BAK1, and BIK1 also directly phosphorylates BAK1 and FLS2 in vitro. The flagellin phosphorylation site Thr(237) of BIK1 is required for its phosphorylation on BAK1 and FLS2, suggesting that BIK1 is likely first phosphorylated upon flagellin perception and subsequently transphosphorylates FLS2/BAK1 to propagate flagellin signaling. Importantly, bik1 mutants are compromised in diverse flagellin-mediated responses and immunity to the nonpathogenic bacterial infection. Thus, BIK1 is an essential component in MAMP signal transduction, which links the MAMP receptor complex to downstream intracellular signaling.