Pirayesh Elham, Do Hoa Quynh, Ferreira Garren, Pandhare Akash, Gallardo Zackary Ryan, Jansen Michaela
Medical Student Summer Research Program, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, 79430 USA.
bioRxiv. 2023 Oct 10:2023.10.09.561596. doi: 10.1101/2023.10.09.561596.
Bupropion is an atypical antidepressant and smoking cessation drug which causes adverse effects such as insomnia, irritability, and anxiety. Bupropion inhibits dopamine and norepinephrine reuptake transporters and eukaryotic cation-conducting pentameric ligand-gated ion channels (pLGICs), such as nicotinic acetylcholine (nACh) and serotonin type 3A (5-HT3A) receptors, at clinically relevant concentrations. However, the binding sites and binding mechanisms of bupropion are still elusive. To further understand the inhibition of pLGICs by bupropion, in this work, using a prokaryotic homologue of pLGICs as a model, we examined the inhibitory potency of bupropion in ligand-gated ion channel (GLIC), a proton-gated ion channel. Bupropion inhibited proton-induced currents in GLIC with an inhibitory potency of 14.9 ± 2.0 μM, comparable to clinically attainable concentrations previously shown to also modulate eukaryotic pLGICs. Using single amino acid substitutions in GLIC and two-electrode voltage-clamp recordings, we further determined a binding site for bupropion in the lower third of the first transmembrane segment M1 at residue T214. The sidechain of M1 T214 together with additional residues of M1 and also of M3 of the adjacent subunit have previously been shown to contribute to binding of other lipophilic molecules like allopregnanolone and pregnanolone.
安非他酮是一种非典型抗抑郁药和戒烟药物，会引起失眠、易怒和焦虑等不良反应。在临床相关浓度下，安非他酮会抑制多巴胺和去甲肾上腺素再摄取转运体以及真核阳离子传导五聚体配体门控离子通道（pLGICs），如烟碱型乙酰胆碱（nACh）和5-羟色胺3A（5-HT3A）受体。然而，安非他酮的结合位点和结合机制仍不清楚。为了进一步了解安非他酮对pLGICs的抑制作用，在这项研究中，我们以pLGICs的原核同源物为模型，检测了安非他酮对质子门控离子通道配体门控离子通道（GLIC）的抑制效力。安非他酮抑制GLIC中质子诱导的电流，抑制效力为14.9±2.0μM，与先前显示可调节真核pLGICs的临床可达到浓度相当。通过在GLIC中进行单氨基酸替换和双电极电压钳记录，我们进一步确定了安非他酮在第一个跨膜片段M1的下三分之一处T214残基的结合位点。先前已证明，M1 T214的侧链以及M1的其他残基以及相邻亚基的M3残基有助于结合其他亲脂性分子，如别孕烯醇酮和孕烷醇酮。
