Lee Chien-Hsing, Huang Po-Tsang, Liou Horng-Huei, Lin Mei-Ying, Lou Kuo-Long, Chen Chung-Yi
Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Department of Nursing, Min-Hwei Junior College of Health Care Management, Tainan, 73658, Taiwan.
Institutes of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Graduate Institutes of Oral Biology, Medical College, National Taiwan University, Taipei, 10048, Taiwan.
Biochem Biophys Res Commun. 2016 Apr 22;473(1):303-310. doi: 10.1016/j.bbrc.2016.03.100. Epub 2016 Mar 22.
The ROMK1 (Kir1.1) channel activity is predominantly regulated by intracellular pH (pHi) and phosphatidylinositol 4,5-bisphosphate (PIP2). Although several residues were reported to be involved in the regulation of pHi associated with PIP2 interaction, the detailed molecular mechanism remains unclear. We perform experiments in ROMK1 pHi-gating with electrophysiology combined with mutational and structural analysis. In the present study, non basic residues of C-terminal region (S219, N215, I192, L216 and L220) in ROMK1 channels have been found to mediate channel-PIP2 interaction and pHi gating. Further, our structural results show these residues with an appropriate distance to interact with membrane PIP2. Meanwhile, a cluster of basic residues (R188, R217 and K218), which was previously discovered regarding the interaction with PIP2, exists in this appropriate distance to discriminate the regulation of channel-PIP2 interaction and pHi-gating. This appropriate distance can be observed with high conservation in the Kir channel family. Our results provide insight that an appropriate distance cooperates with the electrostatics interaction of channel-PIP2 to regulate pHi-gating.
ROMK1（Kir1.1）通道活性主要受细胞内pH值（pHi）和磷脂酰肌醇4,5 - 二磷酸（PIP2）调节。尽管有报道称几个残基参与了与PIP2相互作用相关的pHi调节，但详细的分子机制仍不清楚。我们结合突变和结构分析，用电生理学方法对ROMK1的pHi门控进行了实验。在本研究中，已发现ROMK1通道C末端区域的非碱性残基（S219、N215、I192、L216和L220）介导通道与PIP2的相互作用以及pHi门控。此外，我们的结构结果表明这些残基与膜PIP2相互作用的距离合适。同时，先前发现的一组与PIP2相互作用的碱性残基（R188、R217和K218）也在这个合适的距离存在，以区分通道与PIP2相互作用的调节和pHi门控。在Kir通道家族中可以观察到这个合适的距离具有高度保守性。我们的结果提供了这样的见解，即合适的距离与通道 - PIP2的静电相互作用协同调节pHi门控。
