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研究揭示GABA再摄取抑制的结构基础
2022-06-12 22:54
来源：小柯机器人

美国南加州大学Cornelius Gati课题组揭示GABA再摄取抑制的结构基础。2022年6月8日，《自然》杂志在线发表了这项成果。

研究人员表示，γ-氨基丁酸（GABA）转运体1（GAT1）通过在突触小泡释放抑制性神经递质GABA时清除突触间隙来调节中枢神经系统的神经元兴奋。通过抑制GABA再摄取转运体来提高突触间隙中的GABA水平，是治疗神经系统疾病（如癫痫）的一个已有策略。
 
研究人员确定了全长的野生型人类GAT1与其临床使用的抑制剂噻加宾复合的冷冻电镜结构，其有序部分只有60 kDa。结构显示，噻加宾通过阻断GABA释放途径的细胞内门，将GAT1锁定在内向开放的构象中，从而抑制了神经递质的摄取。这些结果提供了关于噻加宾对GAT1混合型抑制的见解，噻加宾是一种重要的抗惊厥药物。它的药效学特征被这些实验数据所证实，表明噻加宾最初与底物结合部位的结合是向外开放的构象，而结构显示药物在向内开放的构象中使转运体停滞，这与两步的抑制机制相一致。
 
GAT1的结构对这一重要神经递质转运体的生物学和药理学提供了重要的见解，并为神经调节剂的合理设计提供了蓝图，同时也改变了人们对具有挑战性膜蛋白的单粒子冷冻电镜的认识。
 
附：英文原文
 
Title: Structural basis of GABA reuptake inhibition

Author: Motiwala, Zenia, Aduri, Nanda Gowtham, Shaye, Hamidreza, Han, Gye Won, Lam, Jordy Homing, Katritch, Vsevolod, Cherezov, Vadim, Gati, Cornelius

Issue&Volume: 2022-06-08

Abstract: γ-Aminobutyric acid (GABA) transporter 1 (GAT1)1 regulates neuronal excitation of the central nervous system by clearing the synaptic cleft of the inhibitory neurotransmitter GABA upon its release from synaptic vesicles. Elevating the levels of GABA in the synaptic cleft, by inhibiting GABA reuptake transporters, is an established strategy to treat neurological disorders, such as epilepsy2. Here we determined the cryo-electron microscopy structure of full-length, wild-type human GAT1 in complex with its clinically used inhibitor tiagabine3, with an ordered part of only 60kDa. Our structure reveals that tiagabine locks GAT1 in the inward-open conformation, by blocking the intracellular gate of the GABA release pathway, and thus suppresses neurotransmitter uptake. Our results provide insights into the mixed-type inhibition of GAT1 by tiagabine, which is an important anticonvulsant medication. Its pharmacodynamic profile, confirmed by our experimental data, suggests initial binding of tiagabine to the substrate-binding site in the outward-open conformation, whereas our structure presents the drug stalling the transporter in the inward-open conformation, consistent with a two-step mechanism of inhibition4. The presented structure of GAT1 gives crucial insights into the biology and pharmacology of this important neurotransmitter transporter and provides blueprints for the rational design of neuromodulators, as well as moving the boundaries of what is considered possible in single-particle cryo-electron microscopy of challenging membrane proteins.

DOI: 10.1038/s41586-022-04814-x

Source: https://www.nature.com/articles/s41586-022-04814-x

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html


本期文章：《自然》：Online/在线发表

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