High-speed AFM reveals accelerated binding of agitoxin-2 to a K+ channel by induced fit
High-speed AFM reveals accelerated binding of agitoxin-2 to a K+ channel by induced fit
复制标题
DOI：
10.1126/sciadv.aax0495
复制
发表时间：
2019-07
期刊：
影响因子：
13.6
通讯作者：
Ayumi Sumino;T. Sumikama;T. Sumikama;T. Uchihashi;T. Uchihashi;S. Oiki
中科院分区：
文献类型：
--
作者：
Ayumi Sumino;T. Sumikama;T. Sumikama;T. Uchihashi;T. Uchihashi;S. Oiki
我们发现，结合agitoxin-2的K+通道使用的诱导配合途径，通过单分子分析，通过高速AFM。蝎毒Agitoxin-2（AgTx 2）是一种有效的K+通道阻断剂。对接模型已经阐明，但目前仍不清楚是否结合动力学描述的两个状态的模型（AgTx 2结合和AgTx 2未绑定）或更复杂的机制，如诱导拟合或构象选择。在这里，我们观察到的结合动力学AgTx 2的KcsA通道，使用高速原子力显微镜。从图像的重复结合和解离的AgTx 2的通道，单分子动力学分析表明，该通道的亲和力AgTx 2的持续结合过程中增加，并在持续解离过程中减少。我们提出了一个四态模型，包括高和低亲和态的通道，与相关的速率常数。一个诱导的适合途径是占主导地位的，加速结合400倍。这是第一个在真实的时间蝎毒素结合的分析成像，这是适用于各种生物动力学，包括通道配体，DNA修饰蛋白，和抗原抗体复合物。
We revealed that binding of agitoxin-2 to a K+ channel uses an induced-fit pathway by single-molecule analysis via high-speed AFM. Agitoxin-2 (AgTx2) from scorpion venom is a potent blocker of K+ channels. The docking model has been elucidated, but it remains unclear whether binding dynamics are described by a two-state model (AgTx2-bound and AgTx2-unbound) or a more complicated mechanism, such as induced fit or conformational selection. Here, we observed the binding dynamics of AgTx2 to the KcsA channel using high-speed atomic force microscopy. From images of repeated binding and dissociation of AgTx2 to the channel, single-molecule kinetic analyses revealed that the affinity of the channel for AgTx2 increased during persistent binding and decreased during persistent dissociation. We propose a four-state model, including high- and low-affinity states of the channel, with relevant rate constants. An induced-fit pathway was dominant and accelerated binding by 400 times. This is the first analytical imaging of scorpion toxin binding in real time, which is applicable to various biological dynamics including channel ligands, DNA-modifier proteins, and antigen-antibody complexes.