The Arabidopsis MIK2 receptor elicits immunity by sensing a conserved signature from phytocytokines and microbes

背景回顾：Sessile plants encode a large number of small peptides and cell surface-resident receptor kinases, most of which have unknown functions. 

主要发现：Here, we report that the Arabidopsis receptor kinase MALE DISCOVERER 1-INTERACTING RECEPTOR-LIKE KINASE 2 (MIK2) recognizes the conserved signature motif of SERINE-RICH ENDOGENOUS PEPTIDEs (SCOOPs) from Brassicaceae plants as well as proteins present in fungal Fusarium spp. and bacterial Comamonadaceae, and elicits various immune responses. 

结果1-SCOOP依赖MIK2：SCOOP signature peptides trigger immune responses and altered root development in a MIK2-dependent manner with a sub-nanomolar sensitivity. 

结果2-SCOOP12与MIK2：SCOOP12 directly binds to the extracellular leucine-rich repeat domain of MIK2 in vivo and in vitro, indicating that MIK2 is the receptor of SCOOP peptides.

结果3-下游信号：Perception of SCOOP peptides induces the association of MIK2 and the coreceptors SOMATIC EMBRYOGENESIS RECEPTOR KINASE 3 (SERK3) and SERK4 and relays the signaling through the cytosolic receptor-like kinases BOTRYTIS-INDUCED KINASE 1 (BIK1) and AVRPPHB SUSCEPTIBLE1 (PBS1)-LIKE 1 (PBL1). 

结论：Our study identifies a plant receptor that bears a dual role in sensing the conserved peptide motif from phytocytokines and microbial proteins via a convergent signaling relay to ensure a robust immune response.

 摘 要 

固着植物会编码许多小肽以及细胞表面上的受体激酶，然而其中大多数的功能未知。本文中，作者报道了拟南芥中的受体激酶MIK2识别来自十字花科的SCOOPs以及真菌镰刀菌和细菌丛毛单胞菌中蛋白的保守信号基序，从而引起各种免疫响应。SCOOP信号多肽诱导免疫响应，并改变根的发育，该过程以亚纳摩尔级别的敏感性依赖于受体激酶MIK2。体内和体外实验均显示，SCOOP12能够直接结合到MIK2的胞外富含亮氨酸重复结构域，说明MIK2是SCOOP多肽的受体。对于SCOOP的感知诱导MIK2与共受体SERK3和SERK4的关联，并通过胞质类受体激酶BIK1和PBL1来继续往下传递信号。本文的研究鉴定了一个植物受体，其能够感知植物细胞因子和微生物蛋白的保守多肽基序，并通过一个收敛性信号转导中继，保证植物中强健免疫响应的建立。