COMPUTATIONAL APPROACHES TO UNDERSTANDING ION CHANNEL GATING

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 膜通道和转运体调节细胞内物质的进出。这些过程必须受到严格的调控，以维持细胞内环境的稳定。因此，渠道和传输器采用封闭和开放的结构就不足为奇了，就像水槽的水龙头可以打开或关闭一样。在这里，我们打算研究Kv1.2电压门控钾通道的中央孔是如何打开和关闭的。人们相信，排列在通道孔内的四个相同的螺旋分开，以允许离子畅通无阻地通过通道，而这四个螺旋聚集在一起，阻止了关闭状态下的流动。对许多钾通道的序列分析表明，在沿着螺旋的特定位置上存在保守的脯氨酸和甘氨酸残基，并被认为在这些残基上发生螺旋弯曲。然而，在开放和闭合状态下，没有相同的电压门控钾通道的高分辨率结构，因此这种弯曲是如何发生的尚不清楚。我们打算使用分子模拟来研究Kv1.2中中心螺旋的内在弯曲能力。从晶体结构构型开始，我们将运行野生型和突变型螺旋的长平衡轨迹，并使用伞状采样沿着我们认为对通道开放和关闭重要的某些反应路径来偏置螺旋。我们将把我们的结果与实验突变分析相比较，试图将螺旋弯曲的能量学与全局通道函数联系起来。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Membrane channels and transporters regulate the entry and exit of material from cells. These processes must be tightly regulated to maintain cellular homeostasis. Therefore, it is not surprising that channels and transporters adopted closed and open conformations much like the faucet of a sink can be on or off. Here we propose to study how the central pore of the Kv1.2 voltage-gated potassium channel opens and closes. It is believed that four identical helices that line the channel pore splay apart to allow unobstructed passage of ions through the channel, and that these four helices come together to block the flow in the closed state. Sequence analysis across many potassium channels shows that there are conserved proline and glycine residues at specific positions along the helix, and it is believed that helix bending occurs at these residues. However, there are no high-resolution structures of the same voltage-gated potassium channel in both the open and closed state, so how this bending occurs is not known. We intend to use molecular simulations to study the intrinsic bending ability of the central helix in Kv1.2. Starting from the crystal structure configuration we will run long equilibrium trajectories of wild-type and mutant helices, and we will use umbrella sampling to bias the helix along certain reaction pathways that we believe to be important for channel opening and closing. We will compare our results with experimental mutation analysis in an attempt to relate the energetics of helix bending to the global channel function.