Alberdi Araitz, Gomis-Perez Carolina, Bernardo-Seisdedos Ganeko, Alaimo Alessandro, Malo Covadonga, Aldaregia Juncal, Lopez-Robles Carlos, Areso Pilar, Butz Elisabeth, Wahl-Schott Christian, Villarroel Alvaro
Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain.
Departament de Farmacología, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain.
J Cell Sci. 2015 Nov 1;128(21):4014-23. doi: 10.1242/jcs.176420. Epub 2015 Sep 10.
We show that the combination of an intracellular bi-partite calmodulin (CaM)-binding site and a distant assembly region affect how an ion channel is regulated by a membrane lipid. Our data reveal that regulation by phosphatidylinositol(4,5)bisphosphate (PIP2) and stabilization of assembled Kv7.2 subunits by intracellular coiled-coil regions far from the membrane are coupled molecular processes. Live-cell fluorescence energy transfer measurements and direct binding studies indicate that remote coiled-coil formation creates conditions for different CaM interaction modes, each conferring different PIP2 dependency to Kv7.2 channels. Disruption of coiled-coil formation by epilepsy-causing mutation decreases apparent CaM-binding affinity and interrupts CaM influence on PIP2 sensitivity.
我们发现，细胞内双组分钙调蛋白（CaM）结合位点与远距离组装区域的组合会影响离子通道如何受到膜脂的调控。我们的数据表明，磷脂酰肌醇（4,5）二磷酸（PIP2）的调控与远离膜的细胞内卷曲螺旋区域对组装的Kv7.2亚基的稳定作用是相互关联的分子过程。活细胞荧光能量转移测量和直接结合研究表明，远程卷曲螺旋的形成创造了不同CaM相互作用模式的条件，每种模式赋予Kv7.2通道不同的PIP2依赖性。导致癫痫的突变破坏卷曲螺旋的形成会降低表观CaM结合亲和力，并中断CaM对PIP2敏感性的影响。
