GRAS Proteins Form a DNA Binding Complex to Induce Gene Expression during Nodulation Signaling in Medicago truncatula
GRAS Proteins Form a DNA Binding Complex to Induce Gene Expression during Nodulation Signaling in Medicago truncatula
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DOI：
10.1105/tpc.108.064501
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发表时间：
2009-02-01
期刊：
影响因子：
11.6
通讯作者：
Oldroyd, Giles E. D.
中科院分区：
文献类型：
--
作者：
Hirsch, Sibylle;Kim, Jiyoung;Oldroyd, Giles E. D.
豆科植物与根瘤菌的共生关系涉及细菌来源的结瘤因子，该因子足以激活宿主植物根上结瘤的形成。根毛细胞对Nod因子的感知诱导钙振荡，钙振荡是Nod因子信号转导途径的一个组成部分。钙振荡的感知是钙和钙调蛋白依赖性蛋白激酶的功能，并且这通过两个GRAS结构域转录调节因子（结瘤信号通路1（NSP 1）和NSP 2）以及结瘤所需的ERF转录因子激活结瘤基因表达。在这里，我们表明，NSP 1和NSP 2形成一个复杂的，是与早期的启动子的reglulin基因。我们表明，NSP 1直接绑定到ENOD启动子通过新的顺式元件AATTT。虽然NSP 1在体外显示出与ENOD 11启动子的直接结合，但这种体内结合需要NSP 2。NSP 1-NSP 2与ENOD 11启动子的结合在Nod因子诱导后增强。NSP 2结构域中负责其与NSP 1相互作用的突变突出了NSP 1-NSP 2杂聚物对于促分化信号传导的重要性。我们的工作揭示了GRAS蛋白复合物与DNA的直接结合，并强调了NSP 1-NSP 2复合物在模式豆科植物蒺藜苜蓿中的有效结合的重要性。
The symbiotic association of legumes with rhizobia involves bacterially derived Nod factor, which is sufficient to activate the formation of nodules on the roots of the host plant. Perception of Nod factor by root hair cells induces calcium oscillations that are a component of the Nod factor signal transduction pathway. Perception of the calcium oscillations is a function of a calcium- and calmodulin-dependent protein kinase, and this activates nodulation gene expression via two GRAS domain transcriptional regulators, Nodulation Signaling Pathway1 (NSP1) and NSP2, and an ERF transcription factor required for nodulation. Here, we show that NSP1 and NSP2 form a complex that is associated with the promoters of early nodulin genes. We show that NSP1 binds directly to ENOD promoters through the novel cis-element AATTT. While NSP1 shows direct binding to the ENOD11 promoter in vitro, this association in vivo requires NSP2. The NSP1-NSP2 association with the ENOD11 promoter is enhanced following Nod factor elicitation. Mutations in the domain of NSP2 responsible for its interaction with NSP1 highlight the significance of the NSP1-NSP2 heteropolymer for nodulation signaling. Our work reveals direct binding of a GRAS protein complex to DNA and highlights the importance of the NSP1-NSP2 complex for efficient nodulation in the model legume Medicago truncatula.