2NMR

An unusual twin-His arrangement in the pore of ammonia channels is essential for substrate conductance

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.195 
  • R-Value Work: 0.164 
  • R-Value Observed: 0.166 

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This is version 1.3 of the entry. See complete history. 


Literature

An unusual twin-his arrangement in the pore of ammonia channels is essential for substrate conductance

Javelle, A., Lupo, D., Zheng, L., Li, X.-D., Winkler, F.K., Merrick, M.

(2006) J Biol Chem 281: 39492-39498

  • DOI: 10.1074/jbc.M608325200
  • Primary Citation of Related Structures:  
    2NMR, 2NOP, 2NPK, 2NPJ, 2NPG, 2NPE, 2NPD, 2NOW, 2NPC

  • PubMed Abstract: 

    • Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved h ...

    Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved histidine residues in the pore have been proposed to be necessary for ammonia conductance. By analyzing 14 engineered polar and non-polar variants of these histidines, in Escherichia coli AmtB, we show that both histidines are absolutely required for optimum substrate conductance. Crystal structures of variants confirm that substitution of the histidine residues does not affect AmtB structure. In a subgroup of Amt proteins, found only in fungi, one of the histidines is replaced by glutamate. The equivalent substitution in E. coli AmtB is partially active, and the structure of this variant suggests that the glutamate side chain can make similar interactions to those made by histidine.

    Organizational Affiliation: 

    Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich, Norfolk, NR4 7UH, United Kingdom.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Ammonia channel A424Escherichia coliMutation(s): 0 
Gene Names: amtB
Find proteins for P69681 (Escherichia coli (strain K12))
Explore P69681 
Go to UniProtKB:  P69681
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4
Download Ideal Coordinates CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L		 Ligand Interaction
GOL
Query on GOL
Download Ideal Coordinates CCD File 
A
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N		 Ligand Interaction
ACT
Query on ACT
Download Ideal Coordinates CCD File 
A
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.195 
  • R-Value Work: 0.164 
  • R-Value Observed: 0.166 
  • Space Group: P 63
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 109.799α = 90
b = 109.799β = 90
c = 84.407γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
MAR345data collection
XDSdata reduction
XSCALEdata scaling
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-11-14
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2017-10-18
    Changes: Refinement description