Conformational changes in a mammalian voltage-dependent potassium channel inactivation peptide
Conformational changes in a mammalian voltage-dependent potassium channel inactivation peptide
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DOI：
10.1021/bi972350c
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发表时间：
1998-02-10
期刊：
影响因子：
2.9
通讯作者：
Srai, SKS
中科院分区：
文献类型：
--
作者：
Abbott, GW;Mercer, EAJ;Srai, SKS
应用合成失活“球”肽恢复失活缺失突变体电压门控钾（K-v）通道的快速失活。利用傅里叶变换红外和圆二色光谱，我们研究了合成K(v)3.4通道球肽的结构，以及在一系列与球畴功能相关的环境下的结构。在还原条件下，球肽在水溶液中不含α -螺旋或β -片，但当与阴离子脂质或洗涤剂共溶时，为了模拟球结构域在通道失活过程中遇到的环境，球肽采用部分β -片结构。K(v)3.4球肽的氧化促进了Cys(6)和Cys（24）之间形成二硫键，并在水溶液中采用部分-薄片结构；在一定的环境下，氧化球肽采用β -片的倾向通常大于还原球肽。K(v)3.4球肽结构的THREADER模型预测了一个β -发夹状构象，这与球肽的循环排列的光谱分析表明的结构很好地对应，一个V7E突变体K(v)3.4球肽类似于非灭活的Shaker B L7E突变体球肽，无论在什么环境下，无论氧化状态如何，都不能采用β -结构。结果表明，K(v)3.4球结构域在通道失活过程中发生了构象变化，可能暗示了K(v)3.4球结构域在体内对分子内二硫键的形成具有新的调节作用。
Fast inactivation is restored in inactivation deletion mutant voltage-gated potassium (K-v) channels by application of synthetic inactivation 'ball' peptide. Using Fourier transform infrared and circular dichroism spectroscopy, we have investigated the structure of synthetic K(v)3.4 channel ball peptide, in a range of environments relevant to the function of the ball domain. The ball peptide contains no alpha-helix or beta-sheet in reducing conditions in aqueous solution, but when cosolubilized with anionic lipid or detergent in order to mimic the environment which the ball domain encounters during channel inactivation, the ball peptide adopts a partial beta-sheet structure. Oxidation of the K(v)3.4 ball peptide facilitates formation of a disulfide bond between Cys(6) and Cys(24) and adoption of a partial beta-sheet structure in aqueous solution; the tendency of the oxidized ball peptide to adopt beta-sheet is generally greater than that of the reduced ball peptide in a given environment. THREADER modeling of the K(v)3.4 ball peptide structure predicts a beta-hairpin-like conformation which corresponds well to the structure suggested by spectroscopic analysis of the ball peptide in its cyclic arrangement, A V7E mutant K(v)3.4 ball peptide analogue of the noninactivating Shaker B L7E mutant ball peptide cannot adopt beta-structure whatever the environment, and regardless of oxidation state. The results suggest that the K(v)3.4 ball domain undergoes a conformational change during channel inactivation and may implicate a novel regulatory role for intramolecular disulfide bond formation in the K(v)3.4 ball domain in vivo.