Gating of Shaker-type channels requires the flexibility of S6 caused by prolines
Gating of Shaker-type channels requires the flexibility of S6 caused by prolines
复制标题
DOI：
10.1074/jbc.m306097200
复制
发表时间：
2003-12-12
影响因子：
4.8
通讯作者：
Snyders, DJ
中科院分区：
文献类型：
--
作者：
Labro, AJ;Raes, AL;Snyders, DJ
最近的结晶的电压门控K+通道的结构，这些通道的洞察，但没有解决的问题的位置和操作的门。在Shaker通道的S6区段中的保守的PXP基序已被提出有助于细胞内门控结构。为了研究该基序在α-螺旋不稳定中的作用，两种脯氨酸都被替换以促进α-螺旋（丙氨酸）或允许柔性构型（甘氨酸）。这些取代是非功能性的或导致通道门控的急剧改变，突出了这些脯氨酸的重要作用。结合这些突变与脯氨酸取代扫描表明，脯氨酸残基在中段的S6所需的功能，但不一定在整个进化保守的位置。这些结果表明，由PXP基序引起的S6 α-螺旋的不稳定或弯曲显然产生了柔性“铰链”，其允许在通道门控和打开期间较低的S6区段的移动。
The recent crystallization of a voltage-gated K+ channel has given insight into the structure of these channels but has not resolved the issues of the location and the operation of the gate. The conserved PXP motif in the S6 segment of Shaker channels has been proposed to contribute to the intracellular gating structure. To investigate the role of this motif in the destabilization of the alpha-helix, both prolines were replaced to promote an alpha-helix (alanine) or to allow a flexible configuration (glycine). These substitutions were nonfunctional or resulted in drastically altered channel gating, highlighting an important role of these prolines. Combining these mutations with a proline substitution scan demonstrated that proline residues in the midsection of S6 are required for functionality, but not necessarily at the positions conserved throughout evolution. These results indicate that the destabilization or bending of the S6 alpha-helix caused by the PXP motif apparently creates a flexible "hinge" that allows movement of the lower S6 segment during channel gating and opening.