1U77 image
Deposition Date 2004-08-02
Release Date 2004-09-21
Last Version Date 2024-10-09
Entry Detail
PDB ID:
1U77
Keywords:
TRANSPORT PROTEIN
Title:
Crystal Structure of Ammonia Channel AmtB from E. Coli
Biological Source:
Source Organism:
Escherichia coli (Taxon ID: 562)
Host Organism:
Escherichia coli
Method Details:
Experimental Method:
X-RAY DIFFRACTION
Resolution:
2.00 Å
R-Value Free:
0.20
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
P 63
1U77 validation report
Macromolecular Entities
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Probable ammonium transporter
Gene (Uniprot):amtB
Mutations:S68F,P126S,L255K
Chain IDs:A
Chain Length:385
Number of Molecules:1
Biological Source:Escherichia coli
UniProt ID:P69681 Pfam ID:PF00909
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
MSE A MET SELENOMETHIONINE
Primary Citation
Mechanism of ammonia transport by Amt/MEP/Rh: structure of AmtB at 1.35 A
Science 305 1587 1594 (2004)
PMID: 15361618 DOI: 10.1126/science.1101952

Abstact

The first structure of an ammonia channel from the Amt/MEP/Rh protein superfamily, determined to 1.35 angstrom resolution, shows it to be a channel that spans the membrane 11 times. Two structurally similar halves span the membrane with opposite polarity. Structures with and without ammonia or methyl ammonia show a vestibule that recruits NH4+/NH3, a binding site for NH4+, and a 20 angstrom-long hydrophobic channel that lowers the NH4+ pKa to below 6 and conducts NH3. Favorable interactions for NH3 are seen within the channel and use conserved histidines. Reconstitution of AmtB into vesicles shows that AmtB conducts uncharged NH3.

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Primary Citation of related structures
1U77