Exploration of the Peptide Recognition of an Amiloride-sensitive FMRFamide Peptide-gated Sodium Channel
Exploration of the Peptide Recognition of an Amiloride-sensitive FMRFamide Peptide-gated Sodium Channel
复制标题
阿米洛利敏感的 FMRF 酰胺肽门控钠通道的肽识别探索
DOI：
10.1074/jbc.m115.710251
复制
发表时间：
2016-04-01
影响因子：
4.8
通讯作者：
Yu, Ye
中科院分区：
文献类型：
--
作者：
Niu, You-Ya;Yang, Yang;Yu, Ye
FMRFamide（Phe-Met-Arg-Phe-NH 2）激活钠通道（FaNaC）是无脊椎动物中由内源性四肽激活的阿米洛利敏感性钠通道，属于上皮钠通道/变性蛋白（ENaC/DEG）超家族。ENaC/DEG超家族在其激活方式上明显不同，例如通过机械刺激或组织酸中毒自发打开或门控。近年来，研究发现许多ENaC/DEG通道可以被小分子或多肽激活，这表明配体门控可能是ENaC/DEG超家族的一个重要特征。肽配体对通道门控的控制可能是该超家族中一个古老的配体门控特征。因此，研究FaNaC通道的肽识别将促进我们对这个离子通道超家族的配体门控特性的理解。在这里，我们证明，Tyr-131，Asn-134，Asp-154，和Ile-160，位于假定的上指结构域的Haciaspersa FaNaC（HaFaNaC）通道，是该离子通道的肽识别的关键残基。ENaC/DEG超家族中的两个HaFaNaC特异性插入基序，位于上拇指结构域的推定的α 4-α 5接头和上关节结构域的α 6-α 7接头，对于HaFaNaC通道的肽识别也是必需的。化学修饰和双突变循环分析进一步表明，这两个特定的插入物和上指结构域中的关键残基一起参与HaFaNaC通道的肽识别。该配体识别位点与酸敏感离子通道（ASIC）的不同之处在于识别位点和通道门之间的距离较长，携带关于配体门控和离子通道的三聚体ENaC/DEG超家族的进化的有用信息。
FMRFamide (Phe-Met-Arg-Phe-NH2)-activated sodium channel (FaNaC) is an amiloride-sensitive sodium channel activated by endogenous tetrapeptide in invertebrates, and belongs to the epithelial sodium channel/degenerin (ENaC/DEG) superfamily. The ENaC/DEG superfamily differs markedly in its means of activation, such as spontaneously opening or gating by mechanical stimuli or tissue acidosis. Recently, it has been observed that a number of ENaC/DEG channels can be activated by small molecules or peptides, indicating that the ligand-gating may be an important feature of this superfamily. The peptide ligand control of the channel gating might be an ancient ligand-gating feature in this superfamily. Therefore, studying the peptide recognition of FaNaC channels would advance our understanding of the ligand-gating properties of this superfamily of ion channels. Here we demonstrate that Tyr-131, Asn-134, Asp-154, and Ile-160, located in the putative upper finger domain of Helix aspersa FaNaC (HaFaNaC) channels, are key residues for peptide recognition of this ion channel. Two HaFaNaC specific-insertion motifs among the ENaC/DEG superfamily, residing at the putative alpha 4-alpha 5 linker of the upper thumb domain and the alpha 6-alpha 7 linker of the upper knuckle domain, are also essential for the peptide recognition of HaFaNaC channels. Chemical modifications and double mutant cycle analysis further indicated that those two specific inserts and key residues in the upper finger domain together participate in peptide recognition of HaFaNaC channels. This ligand recognition site is distinct from that of acid-sensing ion channels (ASICs) by a longer distance between the recognition site and the channel gate, carrying useful information about the ligand gating and the evolution of the trimeric ENaC/DEG superfamily of ion channels.