Timing of CFTR Pore Opening and Structure of Its Transition State
Timing of CFTR Pore Opening and Structure of Its Transition State
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DOI：
10.1016/j.cell.2015.09.052
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发表时间：
2015-10
期刊：
影响因子：
64.5
通讯作者：
B. Sorum;Dávid Czégé;László Csanády
中科院分区：
文献类型：
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作者：
B. Sorum;Dávid Czégé;László Csanády
在囊性纤维化(CF)患者中，氯离子通道发生突变，孔的打开与ATP结合诱导的两个胞质核苷酸结合域(NBD)的二聚化和ATP水解后二聚体的破坏有关。由于其高能过渡态，cftr的打开速度异常缓慢，而cf突变ΔF508进一步减慢了cftr的打开速度。在这里，我们利用缺乏水解的CFTR突变体D1370N的平衡门控，并应用速率平衡自由能关系分析来估计不同蛋白质区域中开放运动的相对时间。我们发现沿蛋白质纵向轴的运动具有明显的方向性，并确定了一个开放的过渡态结构，形成了NBD二聚体，但孔仍然关闭。因此，nbd/孔域界面上的菌株，ΔF508突变位点，是开放的能量屏障。我们的发现表明，在ΔF508-cftr中，有一个治疗机会从药理上稳定这种过渡态结构，以纠正其开放缺陷，这是恢复cftr功能的关键一步。
In CFTR, the chloride ion channel mutated in cystic fibrosis (CF) patients, pore opening is coupled to ATP-binding-induced dimerization of two cytosolic nucleotide binding domains (NBDs) and closure to dimer disruption following ATP hydrolysis. CFTR opening rate, unusually slow because of its high-energy transition state, is further slowed by CF mutation ΔF508. Here, we exploit equilibrium gating of hydrolysis-deficient CFTR mutant D1370N and apply rate-equilibrium free-energy relationship analysis to estimate relative timing of opening movements in distinct protein regions. We find clear directionality of motion along the longitudinal protein axis and identify an opening transition-state structure with the NBD dimer formed but the pore still closed. Thus, strain at the NBD/pore-domain interface, the ΔF508 mutation locus, underlies the energetic barrier for opening. Our findings suggest a therapeutic opportunity to stabilize this transition-state structure pharmacologically in ΔF508-CFTR to correct its opening defect, an essential step toward restoring CFTR function.