2WSX

Crystal Structure of Carnitine Transporter from Escherichia coli


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.5 Å
  • R-Value Free: 0.271 
  • R-Value Work: 0.237 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural Basis of Na(+)-Independent and Cooperative Substrate/Product Antiport in Cait.

Schulze, S.Koster, S.Geldmacher, U.Terwisscha Van Scheltinga, A.C.Kuhlbrandt, W.

(2010) Nature 467: 233

  • DOI: 10.1038/nature09310
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Transport of solutes across biological membranes is performed by specialized secondary transport proteins in the lipid bilayer, and is essential for life. Here we report the structures of the sodium-independent carnitine/butyrobetaine antiporter CaiT ...

    Transport of solutes across biological membranes is performed by specialized secondary transport proteins in the lipid bilayer, and is essential for life. Here we report the structures of the sodium-independent carnitine/butyrobetaine antiporter CaiT from Proteus mirabilis (PmCaiT) at 2.3-A and from Escherichia coli (EcCaiT) at 3.5-A resolution. CaiT belongs to the family of betaine/carnitine/choline transporters (BCCT), which are mostly Na(+) or H(+) dependent, whereas EcCaiT is Na(+) and H(+) independent. The three-dimensional architecture of CaiT resembles that of the Na(+)-dependent transporters LeuT and BetP, but in CaiT a methionine sulphur takes the place of the Na(+) ion to coordinate the substrate in the central transport site, accounting for Na(+)-independent transport. Both CaiT structures show the fully open, inward-facing conformation, and thus complete the set of functional states that describe the alternating access mechanism. EcCaiT contains two bound butyrobetaine substrate molecules, one in the central transport site, the other in an extracellular binding pocket. In the structure of PmCaiT, a tryptophan side chain occupies the transport site, and access to the extracellular site is blocked. Binding of both substrates to CaiT reconstituted into proteoliposomes is cooperative, with Hill coefficients up to 1.7, indicating that the extracellular site is regulatory. We propose a mechanism whereby the occupied regulatory site increases the binding affinity of the transport site and initiates substrate translocation.


    Organizational Affiliation

    Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
L-CARNITINE/GAMMA-BUTYROBETAINE ANTIPORTER
A, B, C
504Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: caiT (yaaP)
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Betaine/Choline/Carnitine Transporter (BCCT) Family
Protein: 
CaiT carnitine transporter
Find proteins for P31553 (Escherichia coli (strain K12))
Go to UniProtKB:  P31553
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NM2
Query on NM2

Download SDF File 
Download CCD File 
A, B, C
3-CARBOXY-N,N,N-TRIMETHYLPROPAN-1-AMINIUM
C7 H16 N O2
JHPNVNIEXXLNTR-UHFFFAOYSA-O
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
NM2Kd: 3900000 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.5 Å
  • R-Value Free: 0.271 
  • R-Value Work: 0.237 
  • Space Group: P 32
Unit Cell:
Length (Å)Angle (°)
a = 124.200α = 90.00
b = 124.200β = 90.00
c = 154.630γ = 120.00
Software Package:
Software NamePurpose
SCALAdata scaling
PHENIXrefinement
XDSdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-09-08
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance