Modeling of the structure and functional mechanisms of v

在过去的一年里，我们开发了Shaker、KvAP、HERG和NaChBac通道在静止、开放和许多过渡构象中的跨膜和细胞外片段的结构模型。对嵌入在脂质双层中的这些通道进行了分子动力学模拟，以评估和改进模型。这些模型受到最近获得的实验数据的限制；例如，Kv1.2通道的晶体结构，KvAP通道的电子顺磁共振(EPR)研究，蝎子BeKM1毒素与HERG通道结合的热力学循环突变研究，以及钙通道孔的半胱氨酸扫描突变(SCAM)研究。我们已经证明，我们在1986年首次提出的S4电压传感器片段随电压变化的螺旋模型与几乎所有的实验结果和能量标准是一致的，包括使用分子动力学模拟进行分析。NaChBac通道是一种原核生物Na+通道，与K+、Ca~(2+)和Na~+通道有相似之处。我们是第一个在原核序列数据库中鉴定该序列的小组。从那时起，它得到了表达，其性质也得到了昂贵的研究。目前正在努力解决其晶体结构问题。我们开发了NaChBac的模型，主要是用它作为踏脚石来模拟更复杂的真核细胞的钙和钠离子通道。我们使用NaChBac模型作为模板结构，建立了人和真菌钙通道的同源模型。我们正在与实验者合作测试这些模型，并使用它们来分析钙通道阻滞剂的分子药理学。

During the last year, we have developed structural models of the transmembrane and extracellular segments of Shaker, KvAP, hERG, and NaChBac channels in resting, open, and numerous transition conformations. Molecular dynamic simulations of these channels embedded in a lipid bilayer were performed to evaluate and refine the models. The models were constrained by recently obtained experimental data; e.g., the crystal structure of the Kv1.2 channel, electron paramagnetic resonance (EPR) studies of KvAP channels, thermodynamic cyclic mutagenesis studies of the binding of BeKM1 toxin from scorpions to the hERG channel, and cysteine scanning mutagenesis (SCAM) studies of Ca2+ channel pores. We have demonstrated that the 'helical screw' model for the voltage-dependent movement of the S4 voltage-sensor segment that we proposed first in 1986, is consistent with virtually all experimental results and with energetic criteria, including analyses using molecular dynamic simulations. The NaChBac channel is a prokaryotic Na+ channel that has similarities to K+, Ca2+, and Na+ channels. We were the first group to identify this sequence in the prokaryotic sequence data base. Since then, it has been expressed and its properties have been studied expensively. Efforts are underway to solve its crystal structure. We developed models of NaChBac, primarily to use it as a stepping stone to model more complex eukaryotic Ca2+ and Na+ channels. We have used the NaChBac models as template structures to develop homology models of human and fungal Ca2+ channels. We are collaborating with experimentalists to test these models and to use them to analyze the molecular pharmacology of Ca2+ channel blockers.