A role for glycine in the gating of plant NMDA-like receptors
A role for glycine in the gating of plant NMDA-like receptors
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DOI：
10.1046/j.1365-313x.2003.01849.x
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发表时间：
2003-09-01
期刊：
影响因子：
7.2
通讯作者：
Campbell, MM
中科院分区：
文献类型：
--
作者：
Dubos, C;Huggins, D;Campbell, MM
氨基酸甘氨酸在哺乳动物中枢神经系统的信号传导中具有明确的作用。例如，甘氨酸与主要的兴奋性神经递质谷氨酸协同作用，通过 N-甲基-D-天冬氨酸 (NMDA) 受体调节钙等离子的流入。植物拥有 NMDA 样受体，通常称为谷氨酸受体 (GLR)，因其假定的配体谷氨酸而命名。此前，甘氨酸并未涉及植物 GLR 活性或植物信号传导的任何其他方面。使用表达水母发光蛋白的转基因拟南芥幼苗监测配体介导的 Ca2+ 胞质浓度 ([Ca2+](cyt)) 的变化，本文提供的数据表明谷氨酸和甘氨酸协同作用以控制植物中配体介导的钙门控。谷氨酸和甘氨酸的协同作用也调节下胚轴伸长。谷氨酸和甘氨酸介导的 [Ca2+](cyt) 瞬时增加以及下胚轴伸长均受到动物 GLR 竞争性抑制剂 6,7-二硝基喹喔啉-2,3 二酮 (DNQX) 的抑制。使用多尺度对接算法结合植物 GLR 配体结合域的分子模型，提供的证据表明甘氨酸而不是谷氨酸可能是大多数植物 GLR 亚基的天然配体。这些发现揭示了甘氨酸信号传导在植物中迄今为止未被考虑的作用，并表明谷氨酸和甘氨酸在 NMDA 样受体上的协同作用早于植物和动物的分化。
The amino acid glycine has a well-established role in signalling in the mammalian central nervous system. For example, glycine acts synergistically with the major excitatory neurotransmitter, glutamate, to regulate the influx of ions such as calcium, through N-methyl-D-aspartate (NMDA) receptors. Plants possess NMDA-like receptors, generically referred to as glutamate receptors (GLRs), named on the basis of their presumed ligand, glutamate. Previously, glycine has not been implicated in plant GLR activity or any other aspect of plant signalling. Using transgenic Arabidopsis seedlings expressing aequorin to monitor ligand-mediated changes in the cytosolic concentration of Ca2+ ([Ca2+](cyt)), the data presented herein show that glutamate and glycine act synergistically to control ligand-mediated gating of calcium in plants. Glutamate and glycine synergism also regulates hypocotyl elongation. Transient increases in [Ca2+](cyt) mediated by glutamate and glycine, as well as hypocotyl elongation, were inhibited by 6,7-dinitroquinoxaline-2,3 dione (DNQX), a competitive inhibitor of animal GLRs. Using a multiscale docking algorithm in combination with a molecular model of the ligand-binding domain of plant GLRs, evidence is provided indicating that glycine, and not glutamate, is likely to be the natural ligand for most plant GLR subunits. These findings uncover a hitherto unconsidered role for glycine signalling in plants, and suggest that the synergistic action of glutamate and glycine at NMDA-like receptors predates the divergence of plants and animals.