CYCLOPS, a mediator of symbiotic intracellular accommodation
CYCLOPS, a mediator of symbiotic intracellular accommodation
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DOI：
10.1073/pnas.0806858105
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发表时间：
2008-12-23
影响因子：
11.1
通讯作者：
Parniske, Martin
中科院分区：
文献类型：
--
作者：
Yano, Koji;Yoshida, Satoko;Parniske, Martin
共生根瘤菌和丛枝菌根真菌对豆科植物根的细胞内感染的起始是通过诱导根表皮细胞核内和周围的钙信号来进行的。虽然钙和钙调蛋白依赖性激酶（CCaMK）是共生根反应的关键介质，钙信号的解码和下游的分子事件知之甚少。在这里，我们的特点百脉根剑水蚤突变体上的微生物感染受到严重抑制。与此相反，根瘤器官发生开始响应根瘤菌，但过早被捕。这种逮捕被克服时，一个放松管制的CCaMK突变体版本引入剑水蚤突变体，赋予发展的全尺寸，自发结节。由于剑水蚤突变体块共生感染，但有能力为结节的发展，他们揭示了一个分叉的信号转导下游的CCaMK。我们通过定位克隆鉴定了CYCLOPS。CYCLOPS携带功能性核定位信号和预测的卷曲螺旋结构域。我们观察到在没有共生刺激的情况下，CCaMK和CYCLOPS在植物和酵母细胞核中的共定位和物理相互作用。重要的是，CYCLOPS是体外CCaMK的磷酸化底物。水稻剑水蚤突变体在AM中受损，水稻CYCLOPS可以恢复莲剑水蚤突变体的共生，表明被子植物之间的功能保守。我们的研究结果表明，CYCLOPS形成一个古老的，预组装的信号转导复合物与CCaMK是专门需要的感染，而器官发生可能需要额外的尚未确定CCaMK相互作用或基板。
The initiation of intracellular infection of legume roots by symbiotic rhizobia bacteria and arbuscular mycorrhiza (AM) fungi is preceded by the induction of calcium signatures in and around the nucleus of root epidermal cells. Although a calcium and calmodulin-dependent kinase (CCaMK) is a key mediator of symbiotic root responses, the decoding of the calcium signal and the molecular events downstream are only poorly understood. Here, we characterize Lotus japonicus cyclops mutants on which microbial infection was severely inhibited. In contrast, nodule organogenesis was initiated in response to rhizobia, but arrested prematurely. This arrest was overcome when a deregulated CCaMK mutant version was introduced into cyclops mutants, conferring the development of full-sized, spontaneous nodules. Because cyclops mutants block symbiotic infection but are competent for nodule development, they reveal a bifurcation of signal transduction downstream of CCaMK. We identified CYCLOPS by positional cloning. CYCLOPS carries a functional nuclear localization signal and a predicted coiled-coil domain. We observed colocalization and physical interaction between CCaMK and CYCLOPS in plant and yeast cell nuclei in the absence of symbiotic stimulation. Importantly, CYCLOPS is a phosphorylation substrate of CCaMK in vitro. Cyclops mutants of rice were impaired in AM, and rice CYCLOPS could restore symbiosis in Lotus cyclops mutants, indicating a functional conservation across angiosperms. Our results suggest that CYCLOPS forms an ancient, preassembled signal transduction complex with CCaMK that is specifically required for infection, whereas organogenesis likely requires additional yet-to-be identified CCaMK interactors or substrates.