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Structure of the Arabidopsis Glutamate Receptor-like Channel GLR3.2 Ligand-Binding Domain
Structure ( IF 5.7 ) Pub Date : 2020-10-06 , DOI: 10.1016/j.str.2020.09.006
Shanti Pal Gangwar 1 , Marriah N Green 2 , Erwan Michard 3 , Alexander A Simon 3 , José A Feijó 3 , Alexander I Sobolevsky 1
Affiliation  

Glutamate receptor-like channels (GLRs) play important roles in numerous plant physiological processes. GLRs are homologous to ionotropic glutamate receptors (iGluRs) that mediate neurotransmission in vertebrates. Here we determine crystal structures of Arabidopsis thaliana GLR3.2 ligand-binding domain (LBD) in complex with glycine and methionine to 1.58- and 1.75-Å resolution, respectively. Our structures show a fold similar to that of iGluRs, but with several secondary structure elements either missing or different. The closed clamshell conformation of GLR3.2 LBD suggests that both glycine and methionine act as agonists. The mutation R133A strongly increases the constitutive activity of the channel, suggesting that the LBD mutated at the residue critical for agonist binding produces a more stable closed clamshell conformation. Furthermore, our structures explain the promiscuity of GLR activation by different amino acids, confirm evolutionary conservation of structure between GLRs and iGluRs, and predict common molecular principles of their gating mechanisms driven by bilobed clamshell-like LBDs.



中文翻译:

拟南芥谷氨酸受体样通道 GLR3.2 配体结合域的结构

谷氨酸受体样通道 (GLR) 在许多植物生理过程中发挥重要作用。GLR 与介导脊椎动物神经传递的离子型谷氨酸受体 (iGluR) 同源。在这里我们确定了拟南芥的晶体结构GLR3.2 配体结合域 (LBD) 与甘氨酸和甲硫氨酸复合,分辨率分别为 1.58 和 1.75 Å。我们的结构显示出与 iGluR 相似的折叠,但有几个二级结构元素缺失或不同。GLR3.2 LBD 的闭合蛤壳构象表明甘氨酸和甲硫氨酸均作为激动剂。突变 R133A 强烈增加了通道的组成活性,表明在激动剂结合关键的残基处发生突变的 LBD 产生了更稳定的闭合蛤壳构象。此外,我们的结构解释了不同氨基酸对 GLR 激活的混杂性,证实了 GLR 和 iGluR 之间结构的进化保守性,并预测了由双叶蛤壳状 LBD 驱动的门控机制的共同分子原理。

更新日期:2020-10-06
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