4HUQ

Crystal Structure of a transporter


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.217 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Crystal structure of a folate energy-coupling factor transporter from Lactobacillus brevis.

Xu, K.Zhang, M.Zhao, Q.Yu, F.Guo, H.Wang, C.He, F.Ding, J.Zhang, P.

(2013) Nature 497: 268-271

  • DOI: 10.1038/nature12046
  • Primary Citation of Related Structures:  
    4HUQ

  • PubMed Abstract: 
  • ATP-binding cassette (ABC) transporters, composed of importers and exporters, form one of the biggest protein superfamilies that transport a variety of substrates across the membrane, powered by ATP hydrolysis. Most ABC transporters are composed of t ...

    ATP-binding cassette (ABC) transporters, composed of importers and exporters, form one of the biggest protein superfamilies that transport a variety of substrates across the membrane, powered by ATP hydrolysis. Most ABC transporters are composed of two transmembrane domains and two cytoplasmic nucleotide-binding domains. Also, importers from prokaryotes usually have extra solute-binding proteins in the periplasm that are responsible for the binding of substrates. Structures of importers have been reported that suggested a two-state model for the transport mechanism. Energy-coupling factor (ECF) transporters belong to a new class of ATP-binding cassette importers. Each ECF transporter comprises an energy-coupling module consisting of a transmembrane T protein (EcfT), two nucleotide-binding proteins (EcfA and EcfA'), and another transmembrane substrate-specific binding S protein (EcfS). Despite the similarities with ABC transporters, ECF transporters have different organizational and functional properties. The lack of solute-binding proteins in ECF transporters differentiates them clearly from the canonical ABC importers. Previously reported structures of the EcfS proteins RibU and ThiT clearly demonstrated the binding site of substrate riboflavin and thiamine, respectively. However, the organization of the four different components and the transport mechanism of ECF transporters remain unknown. Here we present the structure of an intact folate ECF transporter from Lactobacillus brevis at a resolution of 3 Å. This structure was captured in an inward-facing, nucleotide-free conformation with no bound substrate. The folate-binding protein FolT is nearly parallel to the membrane and is bound almost entirely by EcfT, which adopts an L shape and connects to EcfA and EcfA' through two coupling helices. Two conserved XRX motifs from the coupling helices of EcfT have a vital role in energy coupling by docking into EcfA-EcfA'. We propose a transport model that involves a substantial conformational change of FolT.


    Organizational Affiliation

    National Key Laboratory of Plant Molecular Genetics, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Energy-coupling factor transporter ATP-binding protein EcfA 1A290Lactobacillus brevis ATCC 367Mutation(s): 0 
Gene Names: cbiO1ecfA1LVIS_1661unknown transporterecfA2cbiO2
EC: 3.6.3
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Energy-Coupling Factor (ECF) Transporters
Protein: 
Folate ECF transporter complex
Find proteins for Q03PY6 (Lactobacillus brevis (strain ATCC 367 / JCM 1170))
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Go to UniProtKB:  Q03PY6
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Energy-coupling factor transporter ATP-binding protein EcfA 2B279Lactobacillus brevis ATCC 367Mutation(s): 0 
Gene Names: ecfA2cbiO2LVIS_1662ecfA1cbiO1
EC: 3.6.3 (PDB Primary Data), 7 (UniProt)
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Energy-Coupling Factor (ECF) Transporters
Protein: 
Folate ECF transporter complex
Find proteins for Q03PY5 (Lactobacillus brevis (strain ATCC 367 / JCM 1170))
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Go to UniProtKB:  Q03PY5
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Uncharacterized proteinS174Lactobacillus brevis ATCC 367Mutation(s): 0 
Gene Names: LVIS_0823
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Energy-Coupling Factor (ECF) Transporters
Protein: 
Folate ECF transporter complex
Find proteins for Q03S56 (Lactobacillus brevis (strain ATCC 367 / JCM 1170))
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Go to UniProtKB:  Q03S56
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  • Reference Sequence
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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
Energy-coupling factor transporter transmembrane protein EcfTT280Lactobacillus brevis ATCC 367Mutation(s): 0 
Gene Names: ecfTLVIS_1660
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Energy-Coupling Factor (ECF) Transporters
Protein: 
Folate ECF transporter complex
Find proteins for Q03PY7 (Lactobacillus brevis (strain ATCC 367 / JCM 1170))
Explore Q03PY7 
Go to UniProtKB:  Q03PY7
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.217 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 80.608α = 90
b = 149.004β = 90
c = 170.855γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling
SHELXSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-04-17
    Type: Initial release
  • Version 1.1: 2013-05-01
    Changes: Database references
  • Version 1.2: 2013-05-22
    Changes: Database references