2NPJ

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 Å
  • R-Value Free: 0.168 
  • R-Value Work: 0.157 

wwPDB Validation 3D Report Full Report


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:  

  • 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 conserv ...

    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: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Ammonia channel
A
424Escherichia coli (strain K12)Mutation(s): 1 
Gene Names: amtB (ybaG)
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Channels: Amt/Mep/Rh proteins
Protein: 
AmtB ammonia channel (mutant)
Find proteins for P69681 (Escherichia coli (strain K12))
Go to UniProtKB:  P69681
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

Download SDF File 
Download CCD File 
A
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
IMD
Query on IMD

Download SDF File 
Download CCD File 
A
IMIDAZOLE
C3 H5 N2
RAXXELZNTBOGNW-UHFFFAOYSA-O
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.168 
  • R-Value Work: 0.157 
  • Space Group: P 63
Unit Cell:
Length (Å)Angle (°)
a = 110.512α = 90.00
b = 110.512β = 90.00
c = 84.179γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
XDSdata reduction
XSCALEdata scaling
MOLREPphasing
MAR345data collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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