3B5W

Crystal Structure of Eschericia coli MsbA

Summary for 3B5W

• Entry DOI: 10.2210/pdb3b5w/pdb
• Related: 3B5X 3B5Y 3B5Z 3B60
• Descriptor: Lipid A export ATP-binding/permease protein msbA (1 entity in total)
• Functional Keywords: abc transporter, msba, lipid flippase, atp-binding, hydrolase, inner membrane, lipid transport, membrane, nucleotide-binding, transmembrane, membrane protein
• Biological source: Escherichia coli
• Cellular location: Cell inner membrane; Multi-pass membrane protein: P60752
• Total number of polymer chains: 8
• Total formula weight: 516244.34

Authors

Ward, A.,Reyes, C.L.,Yu, J.,Roth, C.B.,Chang, G. (deposition date: 2007-10-26, release date: 2007-12-04, Last modification date: 2024-02-21)

Primary citation

Ward, A.,Reyes, C.L.,Yu, J.,Roth, C.B.,Chang, G.
Flexibility in the ABC transporter MsbA: Alternating access with a twist.
Proc.Natl.Acad.Sci.Usa, 104:19005-19010, 2007

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.

PubMed: 18024585
DOI: 10.1073/pnas.0709388104

Experimental method

X-RAY DIFFRACTION (5.3 Å)