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PDBsum entry 6v0c
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Lipid transport
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PDB id
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6v0c
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References listed in PDB file
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Key reference
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Title
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Letb structure reveals a tunnel for lipid transport across the bacterial envelope.
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Authors
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G.L.Isom,
N.Coudray,
M.R.Macrae,
C.T.Mcmanus,
D.C.Ekiert,
G.Bhabha.
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Ref.
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Cell, 2020,
181,
653.
[DOI no: ]
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PubMed id
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Abstract
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Gram-negative bacteria are surrounded by an outer membrane composed of
phospholipids and lipopolysaccharide, which acts as a barrier and contributes to
antibiotic resistance. The systems that mediate phospholipid trafficking across
the periplasm, such as MCE (Mammalian Cell Entry) transporters, have not been
well characterized. Our ~3.5 Å cryo-EM structure of the E. coli MCE protein
LetB reveals an ~0.6 megadalton complex that consists of seven stacked rings,
with a central hydrophobic tunnel sufficiently long to span the periplasm.
Lipids bind inside the tunnel, suggesting that it functions as a pathway for
lipid transport. Cryo-EM structures in the open and closed states reveal a
dynamic tunnel lining, with implications for gating or substrate translocation.
Our results support a model in which LetB establishes a physical link between
the two membranes and creates a hydrophobic pathway for the translocation of
lipids across the periplasm.
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