5VRE

Crystal structure of a lysosomal potassium-selective channel TMEM175 homolog from Chamaesiphon Minutus

5VRE の概要

• エントリーDOI: 10.2210/pdb5vre/pdb
• 分子名称: Putative integral membrane protein (1 entity in total)
• 機能のキーワード: potassium channel, transport protein
• 由来する生物種: Chamaesiphon minutus PCC 6605
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 90778.47

構造登録者

Lee, C.,Guo, J.,Jiang, Y. (登録日: 2017-05-10, 公開日: 2017-07-19, 最終更新日: 2024-03-13)

主引用文献

Lee, C.,Guo, J.,Zeng, W.,Kim, S.,She, J.,Cang, C.,Ren, D.,Jiang, Y.
The lysosomal potassium channel TMEM175 adopts a novel tetrameric architecture.
Nature, 547:472-475, 2017

PubMed Abstract: TMEM175 is a lysosomal K channel that is important for maintaining the membrane potential and pH stability in lysosomes. It contains two homologous copies of a six-transmembrane-helix (6-TM) domain, which has no sequence homology to the canonical tetrameric K channels and lacks the TVGYG selectivity filter motif found in these channels. The prokaryotic TMEM175 channel, which is present in a subset of bacteria and archaea, contains only a single 6-TM domain and functions as a tetramer. Here, we present the crystal structure of a prokaryotic TMEM175 channel from Chamaesiphon minutus, CmTMEM175, the architecture of which represents a completely different fold from that of canonical K channels. All six transmembrane helices of CmTMEM175 are tightly packed within each subunit without undergoing domain swapping. The highly conserved TM1 helix acts as the pore-lining inner helix, creating an hourglass-shaped ion permeation pathway in the channel tetramer. Three layers of hydrophobic residues on the carboxy-terminal half of the TM1 helices form a bottleneck along the ion conduction pathway and serve as the selectivity filter of the channel. Mutagenesis analysis suggests that the first layer of the highly conserved isoleucine residues in the filter is primarily responsible for channel selectivity. Thus, the structure of CmTMEM175 represents a novel architecture of a tetrameric cation channel whose ion selectivity mechanism appears to be distinct from that of the classical K channel family.

PubMed: 28723891
DOI: 10.1038/nature23269

実験手法

X-RAY DIFFRACTION (3.299 Å)