Subunit interfaces contribute differently to activation and allosteric modulation of neuronal nicotinic acetylcholine receptors.
Subunit interfaces contribute differently to activation and allosteric modulation of neuronal nicotinic acetylcholine receptors.
复制标题
亚基界面对神经元烟碱乙酰胆碱受体的激活和变构调节有不同的贡献。
DOI：
10.1016/j.neuropharm.2014.11.027
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发表时间：
2015
影响因子：
4.7
通讯作者：
Levandoski,MarkM
中科院分区：
文献类型：
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作者：
Short,CaitlinA;Cao,AngelaT;Wingfield,MollyA;Doers,MatthewE;Jobe,EmilyM;Wang,Nan;Levandoski,MarkM
神经元烟碱乙酰胆碱受体（nachr）广泛分布于神经系统，参与许多正常和病理过程。nachr变构的结构决定因素尚不清楚。一类nAChR变构调节剂，包括小分子morantel (Mor)，在结构上与典型激动剂位点同源，但存在于β(+)/α(−)亚基界面。我们假设所有的nAChR亚基在通道激活和变构调制过程中相互移动。因此，我们研究了预计跨越α3β2受体界面的5对残基，1对在激动剂界面，4对在调节剂界面。在这些位置取代半胱氨酸，我们使用二硫捕获来干扰受体功能。α3Y168 -β2D190对，涉及β2亚基的C环区域，介导调节和激动剂激活，因为在氧化（H2O2）处理后，诱发电流减少了50%。在规范位点下方的α3S125 -β2Q39对也参与通道激活，这与先前对肌肉型受体的研究一致；然而，这一对对ACh激活和Mor调制（电流分别下降60%和80%）的敏感性不同。α3Q37 -β2A127和α3E173 -β2R46对均处于非规范界面，氧化后电流增加，表明亚基运动不对称。总之，我们从二硫捕获和进一步的突变分析中得出的结果表明，亚基界面运动对nachr的变构调节很重要，但这两种类型的界面对受体激活的贡献并不相同。
Neuronal nicotinic acetylcholine receptors (nAChRs) are widely distributed in the nervous system and are implicated in many normal and pathological processes. The structural determinants of allostery in nAChRs are not well understood. One class of nAChR allosteric modulators, including the small molecule morantel (Mor), acts from a site that is structurally homologous to the canonical agonist site but exists in the β(+)/α(−) subunit interface. We hypothesized that all nAChR subunits move with respect to each other during channel activation and allosteric modulation. We therefore studied five pairs of residues predicted to span the interfaces of α3β2 receptors, one at the agonist interface and four at the modulator interface. Substituting cysteines in these positions, we used disulfide trapping to perturb receptor function. The pair α3Y168–β2D190, involving the C loop region of the β2 subunit, mediates modulation and agonist activation, because evoked currents were reduced up to 50% following oxidation (H2O2) treatment. The pair α3S125–β2Q39, below the canonical site, is also involved in channel activation, in accord with previous studies of the muscle-type receptor; however, the pair is differentially sensitive to ACh activation and Mor modulation (currents decreased 60% and 80%, respectively). The pairs α3Q37–β2A127 and α3E173–β2R46, both in the non-canonical interface, showed increased currents following oxidation, suggesting that subunit movements are not symmetrical. Together, our results from disulfide trapping and further mutation analysis indicate that subunit interface movement is important for allosteric modulation of nAChRs, but that the two types of interfaces contribute unequally to receptor activation.