4ZBM

Crystal structure of Drosophila cyclic nucleotide gated channel pore mimicking NaK mutant


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.204 

wwPDB Validation   3D Report Full Report


This is version 1.5 of the entry. See complete history


Literature

Structural implications of weak Ca2+ block in Drosophila cyclic nucleotide-gated channels.

Lam, Y.L.Zeng, W.Derebe, M.G.Jiang, Y.

(2015) J Gen Physiol 146: 255-263

  • DOI: 10.1085/jgp.201511431
  • Primary Citation of Related Structures:  
    4ZBM

  • PubMed Abstract: 
  • Calcium permeability and the concomitant calcium block of monovalent ion current ("Ca(2+) block") are properties of cyclic nucleotide-gated (CNG) channel fundamental to visual and olfactory signal transduction. Although most CNG channels bear a conserved glutamate residue crucial for Ca(2+) block, the degree of block displayed by different CNG channels varies greatly ...

    Calcium permeability and the concomitant calcium block of monovalent ion current ("Ca(2+) block") are properties of cyclic nucleotide-gated (CNG) channel fundamental to visual and olfactory signal transduction. Although most CNG channels bear a conserved glutamate residue crucial for Ca(2+) block, the degree of block displayed by different CNG channels varies greatly. For instance, the Drosophila melanogaster CNG channel shows only weak Ca(2+) block despite the presence of this glutamate. We previously constructed a series of chimeric channels in which we replaced the selectivity filter of the bacterial nonselective cation channel NaK with a set of CNG channel filter sequences and determined that the resulting NaK2CNG chimeras displayed the ion selectivity and Ca(2+) block properties of the parent CNG channels. Here, we used the same strategy to determine the structural basis of the weak Ca(2+) block observed in the Drosophila CNG channel. The selectivity filter of the Drosophila CNG channel is similar to that of most other CNG channels except that it has a threonine at residue 318 instead of a proline. We constructed a NaK chimera, which we called NaK2CNG-Dm, which contained the Drosophila selectivity filter sequence. The high resolution structure of NaK2CNG-Dm revealed a filter structure different from those of NaK and all other previously investigated NaK2CNG chimeric channels. Consistent with this structural difference, functional studies of the NaK2CNG-Dm chimeric channel demonstrated a loss of Ca(2+) block compared with other NaK2CNG chimeras. Moreover, mutating the corresponding threonine (T318) to proline in Drosophila CNG channels increased Ca(2+) block by 16 times. These results imply that a simple replacement of a threonine for a proline in Drosophila CNG channels has likely given rise to a distinct selectivity filter conformation that results in weak Ca(2+) block.


    Organizational Affiliation

    Department of Physiology and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 Department of Physiology and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 youxing.jiang@utsouthwestern.edu.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Potassium channel proteinA, B97Bacillus cereus ATCC 14579Mutation(s): 0 
Gene Names: BC_0669
Membrane Entity: Yes 
UniProt
Find proteins for Q81HW2 (Bacillus cereus (strain ATCC 14579 / DSM 31 / CCUG 7414 / JCM 2152 / NBRC 15305 / NCIMB 9373 / NCTC 2599 / NRRL B-3711))
Explore Q81HW2 
Go to UniProtKB:  Q81HW2
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ81HW2
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.204 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.907α = 90
b = 67.907β = 90
c = 89.799γ = 90
Software Package:
Software NamePurpose
CNSrefinement
HKL-2000data reduction
HKL-2000data scaling
MOLREPphasing

Structure Validation

View Full Validation Report




Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM079179
Howard Hughes Medical Institute (HHMI)United States--
Welch FoundationUnited StatesGrant I-1578

Revision History  (Full details and data files)

  • Version 1.0: 2015-07-29
    Type: Initial release
  • Version 1.1: 2015-08-26
    Changes: Data collection
  • Version 1.2: 2015-09-02
    Changes: Database references
  • Version 1.3: 2015-09-09
    Changes: Database references
  • Version 1.4: 2017-09-27
    Changes: Author supporting evidence, Derived calculations
  • Version 1.5: 2019-11-20
    Changes: Author supporting evidence