The voltage-dependent motor protein prestin (also known as SLC26A5) is responsible for the electromotive behaviour of outer-hair cells and underlies the cochlear amplifier¹. Knockout or impairment of prestin causes severe hearing loss^2,3,4,5. Despite the key role of prestin in hearing, the mechanism by which mammalian prestin senses voltage and transduces it into cellular-scale movements (electromotility) is poorly understood. Here we determined the structure of dolphin prestin in six distinct states using single-particle cryo-electron microscopy. Our structural and functional data suggest that prestin adopts a unique and complex set of states, tunable by the identity of bound anions (Cl⁻ or SO₄²⁻). Salicylate, a drug that can cause reversible hearing loss, competes for the anion-binding site of prestin, and inhibits its function by immobilizing prestin in a new conformation. Our data suggest that the bound anion together with its coordinating charged residues and helical dipole act as a dynamic voltage sensor. An analysis of all of the anion-dependent conformations reveals how structural rearrangements in the voltage sensor are coupled to conformational transitions at the protein–membrane interface, suggesting a previously undescribed mechanism of area expansion. Visualization of the electromotility cycle of prestin distinguishes the protein from the closely related SLC26 anion transporters, highlighting the basis for evolutionary specialization of the mammalian cochlear amplifier at a high resolution.

电压依赖性运动蛋白 prestin（也称为 SLC26A5）负责外毛细胞的电动行为，是耳蜗放大器的基础¹ 。 prestin 的敲除或损伤会导致严重的听力损失^2,3,4,5 。尽管 prestin 在听力中发挥着关键作用，但哺乳动物 prestin 感知电压并将其转换为细胞尺度运动（电动性）的机制仍知之甚少。在这里，我们使用单粒子冷冻电子显微镜确定了海豚 prestin 在六种不同状态下的结构。我们的结构和功能数据表明 prestin 采用一组独特且复杂的状态，可通过结合阴离子（Cl ^-或 SO ₄ ²⁻ ）的特性进行调节。水杨酸盐是一种可导致可逆性听力损失的药物，它会竞争 prestin 的阴离子结合位点，并通过将 prestin 固定在新的构象中来抑制其功能。我们的数据表明，结合的阴离子与其配位的带电残基和螺旋偶极子一起充当动态电压传感器。对所有阴离子依赖性构象的分析揭示了电压传感器中的结构重排如何与蛋白质-膜界面处的构象转变耦合，这表明了先前未描述的面积扩展机制。 prestin 电动循环的可视化将该蛋白与密切相关的 SLC26 阴离子转运蛋白区分开来，以高分辨率突出了哺乳动物耳蜗放大器进化专门化的基础。