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Electromechanical coupling in the hyperpolarization-activated K~+ channel KAT1

机译：超极化激活的K〜+通道Kat1中的机电耦合

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摘要

Voltage-gated potassium (K-v) channels coordinate electrical signalling and control cell volume by gating in response to membrane depolarization or hyperpolarization. However, although voltage-sensing domains transduce transmembrane electric field changes by a common mechanism involving the outward or inward translocation of gating charges(1-3), the general determinants of channel gating polarity remain poorly understood(4). Here we suggest a molecular mechanism for electromechanical coupling and gating polarity in non-domain-swapped K-v channels on the basis of the cryo-electron microscopy structure of KAT1, the hyperpolarization-activated K-v channel from Arabidopsis thaliana. KAT1 displays a depolarized voltage sensor, which interacts with a closed pore domain directly via two interfaces and indirectly via an intercalated phospholipid. Functional evaluation of KAT1 structure-guided mutants at the sensor-pore interfaces suggests a mechanism in which direct interaction between the sensor and the C-linker hairpin in the adjacent pore subunit is the primary determinant of gating polarity. We suggest that an inward motion of the S4 sensor helix of approximately 5-7 angstrom can underlie a direct-coupling mechanism, driving a conformational reorientation of the C-linker and ultimately opening the activation gate formed by the S6 intracellular bundle. This direct-coupling mechanism contrasts with allosteric mechanisms proposed for hyperpolarization-activated cyclic nucleotide-gated channels(5), and may represent an unexpected link between depolarization- and hyperpolarization-activated channels.The cryo-electron microscopy structure of the hyperpolarization-activated K+ channel KAT1 points to a direct-coupling mechanism between S4 movement and the reorientation of the C-linker.
机译：电压门控钾（K-V）通道通过响应于膜去极化或超极化来坐标电信带和控制电池体积。然而，尽管通过涉及门控电荷（1-3）向外或向内易位的公共机制来改变跨膜电场的跨膜电场，但是通道门控极性的一般决定因素仍然是较差的（4）。在这里，我们建议基于KAT1的冷冻电子显微镜结构，从拟南芥拟南芥的高分子激活的K-V通道中的机电偶联和浇注非域换流的K-V通道中的电机耦合和浇注极性的分子机制。 KAT1显示去极化的电压传感器，其与闭孔域通过两个接口直接与闭孔域相互作用，并通过插入的磷脂间接地与闭合的磷脂间接相互反对。传感器 - 孔隙界面上的KAT1结构引导突变体的功能评估表明了一种机制，其中传感器和相邻孔链亚基的C键合发夹之间的直接相互作用是门控极性的主要决定因素。我们建议，大约5-7埃的S4传感器螺旋的向内运动可以利于直接耦合机构，驱动C键夹的构象重新定向并最终打开由S6细胞内束形成的激活栅极。这种直接偶联机构与针对超极化激活的循环核苷酸门控通道（5）所提出的变构机制形成对比，并且可以代表去极化和超极化激活通道之间的意外联系。高分子化激活的K +的低温电子显微镜结构通道KAT1指向S4运动和C-Linker的重新定向之间的直接耦合机构。

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  • 来源
    《Nature》 |2020年第7814期|145-149|共5页
  • 作者

    Clark Michael David; Contreras Gustavo F.; Shen Rong; Perozo Eduardo;

  • 作者单位

    Univ Chicago Dept Biochem & Mol Biol 920 E 58Th St Chicago IL 60637 USA;

    Univ Chicago Dept Biochem & Mol Biol 920 E 58Th St Chicago IL 60637 USA;

    Univ Chicago Dept Biochem & Mol Biol 920 E 58Th St Chicago IL 60637 USA;

    Univ Chicago Dept Biochem & Mol Biol 920 E 58Th St Chicago IL 60637 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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