Small-angle neutron scattering studies on the AMPA receptor GluA2 in the resting, AMPA-bound and GYKI-53655-bound states.
Small-angle neutron scattering studies on the AMPA receptor GluA2 in the resting, AMPA-bound and GYKI-53655-bound states.
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DOI：
10.1107/s2052252518012186
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发表时间：
2018-11-01
期刊：
影响因子：
3.9
通讯作者：
Kastrup JS
中科院分区：
文献类型：
--
作者：
Larsen AH;Dorosz J;Thorsen TS;Johansen NT;Darwish T;Midtgaard SR;Arleth L;Kastrup JS
本研究利用小角中子散射研究了洗涤剂溶解四聚体全长异离子型谷氨酸受体GluA2在溶液中的行为。结果发现，在静息状态下以及AMPA和负变构调节剂GYKI-53655存在时，GluA2溶液结构优先呈致密形式。AMPA受体GluA2属于嗜离子性谷氨酸受体家族，在中枢神经系统中负责大多数快速兴奋性神经元信号传导。这些受体对记忆和学习很重要，但也与阿尔茨海默病和癫痫等脑部疾病有关。今天，市场上有一种针对AMPA受体的癫痫治疗药物，即这些受体的负变构调节剂。最近，研究人员报道了全长GluA2在静息（载子）、活化和脱敏状态下的晶体结构和低温电镜（cryo-EM）结构。本文利用小角中子散射（SANS）和一种新型的完全匹配的洗涤剂，报道了全长GluA2的溶液结构。研究了静息状态下以及AMPA和负变构调节剂GYKI-53655存在时GluA2溶液的结构。在溶液和中性pH下，SANS数据清楚地表明GluA2在静息状态下呈致密形式。溶液结构与静止状态下的GluA2晶体结构相似，估计最大距离（dmax）为179±11 Å，旋转半径（R g）为61.9±0.4 Å。使用DAMMIF生成的溶液中GluA2的从头算模型清楚地显示了单个结构域，即细胞外n端结构域和配体结合结构域以及跨膜结构域。溶液结构显示，在AMPA或GYKI-53655存在的情况下，GluA2保持致密形式。仅在酸性pH下，AMPA存在时，GluA2的细胞外部分呈更开放的构象（估计dmax为189±5 Å， rg为65.2±0.5 Å），类似于gla2在准质物存在时最开放、脱敏的3级低温电镜结构。总之，本方法学研究可作为未来膜蛋白SANS研究的范例。
In this study, the behaviour of the detergent-solubilized tetrameric, full-length ionotropic glutamate receptor GluA2 in solution was investigated using small-angle neutron scattering. It was found that the GluA2 solution structure is preferentially in a compact form in the resting state as well as in the presence of AMPA and of the negative allosteric modulator GYKI-53655. The AMPA receptor GluA2 belongs to the family of ionotropic glutamate receptors, which are responsible for most of the fast excitatory neuronal signalling in the central nervous system. These receptors are important for memory and learning, but have also been associated with brain diseases such as Alzheimer’s disease and epilepsy. Today, one drug is on the market for the treatment of epilepsy targeting AMPA receptors, i.e. a negative allosteric modulator of these receptors. Recently, crystal structures and cryo-electron microscopy (cryo-EM) structures of full-length GluA2 in the resting (apo), activated and desensitized states have been reported. Here, solution structures of full-length GluA2 are reported using small-angle neutron scattering (SANS) with a novel, fully matched-out detergent. The GluA2 solution structure was investigated in the resting state as well as in the presence of AMPA and of the negative allosteric modulator GYKI-53655. In solution and at neutral pH, the SANS data clearly indicate that GluA2 is in a compact form in the resting state. The solution structure resembles the crystal structure of GluA2 in the resting state, with an estimated maximum distance (D max) of 179 ± 11 Å and a radius of gyration (R g) of 61.9 ± 0.4 Å. An ab initio model of GluA2 in solution generated using DAMMIF clearly showed the individual domains, i.e. the extracellular N-terminal domains and ligand-binding domains as well as the transmembrane domain. Solution structures revealed that GluA2 remained in a compact form in the presence of AMPA or GYKI-53655. At acidic pH only, GluA2 in the presence of AMPA adopted a more open conformation of the extracellular part (estimated D max of 189 ± 5 Å and R g of 65.2 ± 0.5 Å), resembling the most open, desensitized class 3 cryo-EM structure of GluA2 in the presence of quisqualate. In conclusion, this methodological study may serve as an example for future SANS studies on membrane proteins.