Interaction of KCNE subunits with the KCNQ1 K+ channel pore
Interaction of KCNE subunits with the KCNQ1 K+ channel pore
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DOI：
10.1113/jphysiol.2005.100644
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发表时间：
2006-02-01
影响因子：
5.5
通讯作者：
Abbott, GW
中科院分区：
文献类型：
--
作者：
Panaghie, G;Tai, KK;Abbott, GW
KCNQ1 α亚基通过与kcnne辅助亚基MinK和MiRP2共同组装形成功能不同的钾通道。MinK-KCNQ1通道产生缓慢激活的电压依赖性心脏i - k电流。MiRP2-KCNQ1通道在结肠中形成一个组成性的活跃电流。这些对比通道特性的结构基础，以及KCNE亚基调制α亚基的机制，还没有完全了解。在这里，扫描诱变在KCNQ1孔衬S6结构域的338-340位置发现了色氨酸耐受区域，表明暴露区域可能适合与跨膜辅助亚基相互作用。这一假设通过KCNQ1和MinK和MiRP2的膜定位“激活三联体”区域的伴随诱变来验证，以确定相互作用控制KCNQ1激活的残基对。三对突变发挥了巨大的作用，要么消除通道功能，要么消除或恢复对KCNQ1激活的控制。结果将kcnne亚基放置在KCNQ1孔附近，表明MiRP2-72与KCNQ1-338相互作用；mink -59,58与kcnq1 - 339,340。这些数据要么与MinK或MiRP2对S6结构域的扰动相一致，要么与MinK和MiRP2在通道复合体中的不同定位相一致，要么两者兼而有之。此外，研究结果明确表明，MiRP2-72/KCNQ1-338和MinK-58/KCNQ1-340这两个相互作用对于MinK和MiRP2的门控效应的对比是必需的。
KCNQ1 alpha subunits form functionally distinct potassium channels by coassembling with KCNE ancillary subunits MinK and MiRP2. MinK-KCNQ1 channels generate the slowly activating, voltage-dependent cardiac I-Ks current. MiRP2-KCNQ1 channels form a constitutively active current in the colon. The structural basis for these contrasting channel properties, and the mechanisms of alpha subunit modulation by KCNE subunits, are not fully understood. Here, scanning mutagenesis located a tryptophan-tolerant region at positions 338-340 within the KCNQ1 pore-lining S6 domain, suggesting an exposed region possibly amenable to interaction with transmembrane ancillary subunits. This hypothesis was tested using concomitant mutagenesis in KCNQ1 and in the membrane-localized 'activation triplet' regions of MinK and MiRP2 to identify pairs of residues that interact to control KCNQ1 activation. Three pairs of mutations exerted dramatic effects, ablating channel function or either removing or restoring control of KCNQ1 activation. The results place KCNE subunits close to the KCNQ1 pore, indicating interaction of MiRP2-72 with KCNQ1-338; and MinK-59,58 with KCNQ1-339, 340. These data are consistent either with perturbation of the S6 domain by MinK or MiRP2, dissimilar positioning of MinK and MiRP2 within the channel complex, or both. Further, the results suggest specifically that two of the interactions, MiRP2-72/KCNQ1-338 and MinK-58/KCNQ1-340, are required for the contrasting gating effects of MinK and MiRP2.