Plant cells recognize chitin fragments for defense signaling through a plasma membrane receptor
Plant cells recognize chitin fragments for defense signaling through a plasma membrane receptor
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DOI：
10.1073/pnas.0508882103
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发表时间：
2006-07-18
影响因子：
11.1
通讯作者：
Shibuya, Naoto
中科院分区：
文献类型：
--
作者：
Kaku, Hanae;Nishizawa, Yoko;Shibuya, Naoto
几丁质是真菌细胞壁的主要成分，并作为植物和动物先天免疫系统中识别潜在病原体的分子模式。在植物中，已知甲壳素寡糖在包括单子叶植物和双子叶植物的广泛植物细胞中诱导各种防御反应。为了阐明几丁质寡糖激发子的感知和转导的分子机制，从悬浮培养的水稻细胞质膜中分离出一种与该激发子具有高亲和力的结合蛋白。纯化的蛋白质CEBiP的表征以及相应基因的克隆揭示CEBiP实际上是由328个氨基酸残基和聚糖链组成的糖蛋白。预测CEBiP在C末端具有短的跨膜结构域。通过RNA干扰技术敲低CEBiP基因，抑制了几丁质寡糖激发子诱导的氧化爆发和基因应答，表明CEBiP在水稻细胞对几丁质寡糖激发子的感知和转导中起着关键作用。CEBiP的结构分析还表明在CEBiP的细胞外部分中存在两个LysM基序。由于已知LysM基序存在于参与豆科植物和根瘤菌之间的共生信号传导的推定的Nod因子受体激酶中，该结果表明部分同源质膜蛋白参与植物细胞中的防御和共生信号传导。
Chitin is a major component of fungal cell walls and serves as a molecular pattern for the recognition of potential pathogens in the innate immune systems of both plants and animals. In plants, chitin oligosaccharides have been known to induce various defense responses in a wide range of plant cells including both monocots and dicots. To clarify the molecular machinery involved in the perception and transduction of chitin oligosaccharide elicitor, a high-affinity binding protein for this elicitor was isolated from the plasma membrane of suspension-cultured rice cells. Characterization of the purified protein, CEBiP, as well as the cloning of the corresponding gene revealed that CEBiP is actually a glycoprotein consisting of 328 amino acid residues and glycan chains. CEBiP was predicted to have a short membrane spanning domain at the C terminus. Knockdown of CEBiP gene by RNA interference resulted in the suppression of the elicitor-induced oxidative burst as well as the gene responses, showing that CEBiP plays a key role in the perception and transduction of chitin oligosaccharide elicitor in the rice cells. Structural analysis of CEBiP also indicated the presence of two LysM motifs in the extracellular portion of CEBiP. As the LysM motif has been known to exist in the putative Nod-factor receptor kinases involved in the symbiotic signaling between leguminous plants and rhizobial bacteria, the result indicates the involvement of partially homologous plasma membrane proteins both in defense and symbiotic signaling in plant cells.