Abstract：
Here, we characterized the p.Arg583His (R583H) Kv7.1 mutation, identified in two unrelated families suffered from LQT syndrome. This mutation is located in the HС-HD linker of the cytoplasmic portion of the Kv7.1 channel. This linker, together with HD helix are responsible for binding the A-kinase anchoring protein 9 (AKAP9), Yotiao. We studied the electrophysiological characteristics of the mutated channel expressed in CHO-K1 along with KCNE1 subunit and Yotiao protein, using the whole-cell patch-clamp technique. We found that R583H mutation, even at the heterozygous state, impedes IKs activation. Molecular modeling showed that HС and HD helixes of the C-terminal part of Kv7.1 channel are swapped along the C-terminus length of the channel and that R583 position is exposed to the outer surface of HC-HD tandem coiled-coil. Interestingly, the adenylate cyclase activator, forskolin had a smaller effect on the mutant channel comparing with the WT protein, suggesting that R583H mutation may disrupt the interaction of the channel with the adaptor protein Yotiao and, therefore, may impair phosphorylation of the KCNQ1 channel.
摘要：
这里,我们表征了p.Arg583His（R583H）Kv7.1突变，在两个无关的家庭中发现患有LQT综合征。该突变位于Kv7.1通道的细胞质部分的H_HD接头中。这个链接器，与HD螺旋一起负责结合A激酶锚定蛋白9（AKAP9），Yooiao.我们研究了在CHO-K1中表达的突变通道以及KCNE1亚基和Yotiao蛋白的电生理特性，使用全细胞膜片钳技术。我们发现R583H突变,即使在杂合状态，阻碍IKs激活。分子建模表明，Kv7.1通道C端部分的HCd和HD螺旋沿通道的C端长度交换，并且R583位置暴露于HC-HD串联卷曲螺旋的外表面。有趣的是,腺苷酸环化酶激活剂，与WT蛋白相比，毛喉素对突变通道的影响较小，表明R583H突变可能会破坏通道与衔接蛋白Yotiao的相互作用，因此,可能损害KCNQ1通道的磷酸化。
