The binding site for channel blockers that rescue misprocessed human long QT syndrome type 2 ether-a-gogo-related gene (HERG) mutations
The binding site for channel blockers that rescue misprocessed human long QT syndrome type 2 ether-a-gogo-related gene (HERG) mutations
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DOI：
10.1074/jbc.m107345200
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发表时间：
2002-02-15
影响因子：
4.8
通讯作者：
Brown, AM
中科院分区：
文献类型：
--
作者：
Ficker, E;Obejero-Paz, CA;Brown, AM
人类ether-a-gogo相关基因（HERG）K+通道基因突变导致染色体7连锁长QT综合征2型（LQT 2），其特征是心电图QT间期延长和对危及生命的心律失常的易感性增加。LQT 2突变产生功能丧失表型，并通过非或故障通道亚基与野生型亚基在细胞表面的异聚体组装或通过内质网中错误加工的突变HERG通道的保留来降低I-Kr电流。加工不当的突变通常编码通道蛋白，这些蛋白在掺入质膜后发挥功能。因此，折叠缺陷的药理学校正和蛋白质功能的恢复是相当感兴趣的。在这里，我们报告说，交通缺陷孔突变HERG G601 S是由一系列的HERG通道阻断剂，增加细胞表面的表达获救。通过这些药理学伴侣的救援直接与其阻断效力不同。我们使用结构-活性关系和定点突变来定义药理学伴侣的结合位点。我们发现，结合发生在内腔和相关的疏水性和阳离子电荷。拯救是结构域限制性的，因为通道阻断剂不能恢复C末端的两个错误加工突变HERG F805 C和HERG R823 W的运输。我们的研究结果代表了设计药理学伴侣的第一步，这将拯救HERG K+通道而不被阻断。
Mutations in the human ether-a-gogo-related gene (HERG) K+ channel gene cause chromosome 7-linked long QT syndrome type 2 (LQT2), which is characterized by a prolonged QT interval in the electrocardiogram and an increased susceptibility to life-threatening cardiac arrhythmias. LQT2 mutations produce loss-of-function phenotypes and reduce I-Kr currents either by the heteromeric assembly of non- or malfunctioning channel subunits with wild type subunits at the cell surface or by retention of misprocessed mutant HERG channels in the endoplasmic reticulum. Misprocessed mutations often encode for channel proteins that are functional upon incorporation into the plasma membrane. As a result the pharmacological correction of folding defects and restoration of protein function are of considerable interest. Here we report that the trafficking-deficient pore mutation HERG G601S was rescued by a series of HERG channel blockers that increased cell surface expression. Rescue by these pharmacological chaperones varied directly with their blocking potency. We used structure-activity relationships and site-directed mutagenesis to define the binding site of the pharmacological chaperones. We found that binding occurred in the inner cavity and correlated with hydrophobicity and cationic charge. Rescue was domain-restricted because the trafficking of two misprocessed mutations in the C terminus, HERG F805C and HERG R823W, was not restored by channel blockers. Our findings represent a first step toward the design of pharmacological chaperones that will rescue HERG K+ channels without block.