ジャーナル: Structure / 年: 2025 タイトル: Ion coupling and inhibitory mechanisms of the human presynaptic high-affinity choline transporter CHT1. 著者: Yunlong Qiu / Yiwei Gao / Qinru Bai / Yan Zhao / 要旨: In cholinergic neurons, choline is the precursor of the excitatory neurotransmitter acetylcholine (ACh), which plays a fundamental role in the brain. The high-affinity choline transporter, CHT1, ...In cholinergic neurons, choline is the precursor of the excitatory neurotransmitter acetylcholine (ACh), which plays a fundamental role in the brain. The high-affinity choline transporter, CHT1, mediates the efficient recycling of choline to facilitate ACh synthesis in the presynapse. Here, we report high-resolution cryoelectron microscopic (cryo-EM) structures of CHT1 in complex with the inhibitors HC-3 and ML352, the substrate choline, and a substrate-free state. Our structures show distinct binding modes of the inhibitors with different chemical structures, revealing their inhibition mechanisms. Additionally, we observed a chloride ion that directly interacts with the substrate choline, thereby stabilizing its binding with CHT1. Two sodium ions, Na2 and Na3, were clearly identified, which we speculate might be involved in substrate binding and conformational transitions, respectively. Our structures provide molecular insights into the coupling mechanism of ion binding with substrate binding and conformational transitions, promoting our understanding of the ion-coupled substrate transport mechanism.
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名称: Human high-affinity choline transporter CHT1 bound to ML352 under NaCl condition, with sodium ion coordinated. タイプ: COMPLEX / Entity ID: #1 / 由来: RECOMBINANT
分子量
実験値: NO
由来(天然)
生物種: Homo sapiens (ヒト)
由来(組換発現)
生物種: Homo sapiens (ヒト)
緩衝液
pH: 7.5
試料
濃度: 10 mg/ml / 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES 詳細: This sample was obtained from the monodispersed peak fractions of the size-exclusion chromatography.