A stable ATP binding to the nucleotide binding domain is important for reliable gating cycle in an ABC transporter CFTR.
A stable ATP binding to the nucleotide binding domain is important for reliable gating cycle in an ABC transporter CFTR.
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DOI：
10.1007/s12576-010-0102-2
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发表时间：
2010-09
期刊：
影响因子：
--
通讯作者：
Sohma Y
中科院分区：
文献类型：
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作者：
Shimizu H;Yu YC;Kono K;Kubota T;Yasui M;Li M;Hwang TC;Sohma Y
囊性纤维化跨膜传导调节因子（CFTR）阴离子通道是ABC转运蛋白超家族的成员之一，其门控作用依赖于核苷酸结合域（NBD）的ATP依赖性构象变化。反映了对应于两个NBD的二聚化的通道开放状态的数百毫秒持续时间，宏观WT-CFTR电流通常在去除细胞质ATP后显示出快速的单指数松弛。突变的酪氨酸1219，在第二NBD（NBD 2）的ATP结合的关键残基，诱导一个显着的慢相电流松弛，这表明减弱ATP结合亲和力在NBD 2增加的概率稳定的开放状态。慢相有效地减少了更高的亲和力ATP类似物。这些数据表明，正常的CFTR门控循环需要ATP与NBD 2的稳定结合，ATP结合的不稳定性通常会使门控循环在开放状态下停止，推测是通过NBD 2处ATP水解的失败。
Cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, a member of ABC transporter superfamily, gates following ATP-dependent conformational changes of the nucleotide binding domains (NBD). Reflecting the hundreds of milliseconds duration of the channel open state corresponding to the dimerization of two NBDs, macroscopic WT-CFTR currents usually showed a fast, single exponential relaxation upon removal of cytoplasmic ATP. Mutations of tyrosine1219, a residue critical for ATP binding in second NBD (NBD2), induced a significant slow phase in the current relaxation, suggesting that weakening ATP binding affinity at NBD2 increases the probability of the stable open state. The slow phase was effectively diminished by a higher affinity ATP analogue. These data suggest that a stable binding of ATP to NBD2 is required for normal CFTR gating cycle, andthat the instability of ATP binding frequently halts the gating cycle in the open state presumably through a failure of ATP hydrolysis at NBD2.