Structure of glutamate-GABA antiporter GadC

Experimental Data Snapshot

  • Resolution: 3.10 Å
  • R-Value Free: 0.325 
  • R-Value Work: 0.282 
  • R-Value Observed: 0.285 

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Structure and mechanism of a glutamate-GABA antiporter

Ma, D.Lu, P.L.Yan, C.Y.Fan, C.Yin, P.Wang, J.W.Shi, Y.G.

(2012) Nature 483: 632-636

  • DOI: https://doi.org/10.1038/nature10917
  • Primary Citation of Related Structures:  
    4DJI, 4DJK

  • PubMed Abstract: 

    Food-borne hemorrhagic Escherichia coli, exemplified by the strains O157:H7 and O104:H4 (refs 1, 2), require elaborate acid-resistance systems (ARs) to survive the extremely acidic environment such as the stomach (pH ≈ 2). AR2 expels intracellular protons through the decarboxylation of L-glutamate (Glu) in the cytoplasm and exchange of the reaction product γ-aminobutyric acid (GABA) with extracellular Glu. The latter process is mediated by the Glu-GABA antiporter GadC, a representative member of the amino-acid-polyamine-organocation superfamily of membrane transporters. The functional mechanism of GadC remains largely unknown. Here we show, with the use of an in vitro proteoliposome-based assay, that GadC transports GABA/Glu only under acidic conditions, with no detectable activity at pH  values higher than 6.5. We determined the crystal structure of E. coli GadC at 3.1 Å resolution under basic conditions. GadC, comprising 12 transmembrane segments (TMs), exists in a closed state, with its carboxy-terminal domain serving as a plug to block an otherwise inward-open conformation. Structural and biochemical analyses reveal the essential transport residues, identify the transport path and suggest a conserved transport mechanism involving the rigid-body rotation of a helical bundle for GadC and other amino acid antiporters.

  • Organizational Affiliation

    Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua University, Beijing 100084, China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Probable glutamate/gamma-aminobutyrate antiporter
A, B
511Escherichia coli K-12Mutation(s): 0 
Gene Names: gadC
Membrane Entity: Yes 
Find proteins for P63235 (Escherichia coli (strain K12))
Explore P63235 
Go to UniProtKB:  P63235
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP63235
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.10 Å
  • R-Value Free: 0.325 
  • R-Value Work: 0.282 
  • R-Value Observed: 0.285 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 71.962α = 90
b = 106.408β = 90
c = 185.982γ = 90
Software Package:
Software NamePurpose
CBASSdata 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: 2012-03-14
    Type: Initial release
  • Version 1.1: 2012-04-04
    Changes: Database references
  • Version 1.2: 2024-03-20
    Changes: Data collection, Database references