Crystal structure of a membrane protein

Experimental Data Snapshot

  • Resolution: 3.35 Å
  • R-Value Free: 0.274 
  • R-Value Work: 0.248 
  • R-Value Observed: 0.249 

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This is version 1.3 of the entry. See complete history


Structure and molecular mechanism of an anion-selective mechanosensitive channel of small conductance

Zhang, X.Wang, J.Feng, Y.Ge, J.Li, W.Sun, W.Iscla, I.Yu, J.Blount, P.Li, Y.Yang, M.

(2012) Proc Natl Acad Sci U S A 109: 18180-18185

  • DOI: https://doi.org/10.1073/pnas.1207977109
  • Primary Citation of Related Structures:  
    3T9N, 3UDC

  • PubMed Abstract: 

    Mechanosensitive (MS) channels are universal cellular membrane pores. Bacterial MS channels, as typified by MS channel of small conductance (MscS) from Escherichia coli (EcMscS), release osmolytes under hypoosmotic conditions. MS channels are known to be ion selective to different extents, but the underlying mechanism remains poorly understood. Here we identify an anion-selective MscS channel from Thermoanaerobacter tengcongensis (TtMscS). The structure of TtMscS closely resembles that of EcMscS, but it lacks the large cytoplasmic equatorial portals found in EcMscS. In contrast, the cytoplasmic pore formed by the C-terminal β-barrel of TtMscS is larger than that of EcMscS and has a strikingly different pattern of electrostatic surface potential. Swapping the β-barrel region between TtMscS and EcMscS partially switches the ion selectivity. Our study defines the role of the β-barrel in the ion selection of an anion-selective MscS channel and provides a structural basis for understanding the ion selectivity of MscS channels.

  • Organizational Affiliation

    Key Laboratory for Protein Sciences of Ministry of Education, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Small-conductance mechanosensitive channel, C-terminal peptide from Small-conductance mechanosensitive channel
A, B, C, D, E
A, B, C, D, E, F, G
285Caldanaerobacter subterraneus subsp. tengcongensis MB4Escherichia coli K-12
This entity is chimeric
Mutation(s): 0 
Gene Names: MscS
Membrane Entity: Yes 
Find proteins for Q8R6L9 (Caldanaerobacter subterraneus subsp. tengcongensis (strain DSM 15242 / JCM 11007 / NBRC 100824 / MB4))
Explore Q8R6L9 
Go to UniProtKB:  Q8R6L9
Find proteins for P0C0S1 (Escherichia coli (strain K12))
Explore P0C0S1 
Go to UniProtKB:  P0C0S1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupsP0C0S1Q8R6L9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.35 Å
  • R-Value Free: 0.274 
  • R-Value Work: 0.248 
  • R-Value Observed: 0.249 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 96.046α = 90
b = 139.468β = 90
c = 224.113γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-10-31
    Type: Initial release
  • Version 1.1: 2013-06-19
    Changes: Database references
  • Version 1.2: 2017-08-16
    Changes: Refinement description, Source and taxonomy
  • Version 1.3: 2023-11-01
    Changes: Data collection, Database references, Refinement description