Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Predict Membrane 

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 129.25 kDa 
• Atom Count: 1144 
• Modelled Residue Count: 1144 
• Deposited Residue Count: 1164 
• Unique protein chains: 1

3B5X

Crystal Structure of MsbA from Vibrio cholerae

• PDB DOI: 10.2210/pdb3B5X/pdb

• Classification: MEMBRANE PROTEIN
• Organism(s): Vibrio cholerae
• Expression System: Escherichia coli BL21
• Mutation(s): No 
• Membrane Protein: Yes  OPMPDBTMMemProtMDmpstruc


• Deposited: 2007-10-26 Released: 2007-12-04 
• Deposition Author(s): Ward, A., Reyes, C.L., Yu, J., Roth, C.B., Chang, G.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 5.50 Å
• R-Value Free: 0.360 
• R-Value Work: 0.348 

Literature

Flexibility in the ABC transporter MsbA: Alternating access with a twist.

Ward, A., Reyes, C.L., Yu, J., Roth, C.B., Chang, G.

(2007) Proc Natl Acad Sci U S A 104: 19005-19010

• PubMed: 18024585 
• DOI: 10.1073/pnas.0709388104
• Primary Citation of Related Structures:  
  3B5W, 3B5X, 3B5Y, 3B5Z, 3B60


• PubMed Abstract: 
  

ATP-binding cassette (ABC) transporters are integral membrane proteins that translocate a wide variety of substrates across cellular membranes and are conserved from bacteria to humans. Here we compare four x-ray structures of the bacterial ABC lipid flippase, MsbA, trapped in different conformations, two nucleotide-bound structures and two in the absence of nucleotide. Comparison of the nucleotide-free conformations of MsbA reveals a flexible hinge formed by extracellular loops 2 and 3. This hinge allows the nucleotide-binding domains to disassociate while the ATP-binding half sites remain facing each other. The binding of the nucleotide causes a packing rearrangement of the transmembrane helices and changes the accessibility of the transporter from cytoplasmic (inward) facing to extracellular (outward) facing. The inward and outward openings are mediated by two different sets of transmembrane helix interactions. Altogether, the conformational changes between these structures suggest that large ranges of motion may be required for substrate transport.

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Organizational Affiliation: 

Departments of Cell Biology and Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, CB-105, La Jolla, CA 92037, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Lipid A export ATP-binding/permease protein msbA	A, B	582	Vibrio cholerae	Mutation(s): 0  Gene Names: msbA EC: 3.6.3 (PDB Primary Data), 7.5.2.6 (UniProt) Membrane Entity: Yes
UniProt
Find proteins for Q9KQW9 (Vibrio cholerae serotype O1 (strain ATCC 39315 / El Tor Inaba N16961)) Explore Q9KQW9  Go to UniProtKB:  Q9KQW9

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 5.50 Å
• R-Value Free: 0.360 
• R-Value Work: 0.348 
• Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 120.59	α = 90
b = 150.42	β = 90
c = 148.88	γ = 90

Software Package:

Software Name	Purpose
CNS	refinement
PDB_EXTRACT	data extraction
HKL-2000	data reduction
HKL-2000	data scaling
PHASES	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2007-10-26 
• Released Date: 2007-12-04 
Deposition Author(s): Ward, A., Reyes, C.L., Yu, J., Roth, C.B., Chang, G.

Revision History  

• Version 1.0: 2007-12-04
  Type: Initial release
  
• Version 1.1: 2011-07-13
  Changes: Version format compliance