5VRE

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.299 Å
  • R-Value Free: 0.282 
  • R-Value Work: 0.259 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The lysosomal potassium channel TMEM175 adopts a novel tetrameric architecture.

Lee, C.Guo, J.Zeng, W.Kim, S.She, J.Cang, C.Ren, D.Jiang, Y.

(2017) Nature 547: 472-475

  • DOI: 10.1038/nature23269

  • 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 te ...

    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.


    Organizational Affiliation

    Department of Physiology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Putative integral membrane protein
A, B, C, D
203Chamaesiphon minutus (strain ATCC 27169 / PCC 6605)Mutation(s): 0 
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Channels: Potassium, Sodium, & Proton Ion-Selective
Protein: 
TMEM175 lysosomal K+ channel
Find proteins for K9UJK2 (Chamaesiphon minutus (strain ATCC 27169 / PCC 6605))
Go to UniProtKB:  K9UJK2
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.299 Å
  • R-Value Free: 0.282 
  • R-Value Work: 0.259 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 152.660α = 90.00
b = 108.880β = 117.24
c = 119.330γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data scaling
autoSHARPphasing
HKL-2000data reduction
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical SciencesUnited StatesGM079179
Welch FoundationUnited StatesI-1578
Howard Hughes Medical InstituteUnited States--

Revision History 

  • Version 1.0: 2017-07-19
    Type: Initial release
  • Version 1.1: 2017-08-02
    Type: Author supporting evidence, Database references, Structure summary
  • Version 1.2: 2017-11-22
    Type: Refinement description