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-Structure paper
Title | LetB Structure Reveals a Tunnel for Lipid Transport across the Bacterial Envelope. |
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Journal, issue, pages | Cell, Vol. 181, Issue 3, Page 653-664.e19, Year 2020 |
Publish date | Apr 30, 2020 |
Authors | Georgia L Isom / Nicolas Coudray / Mark R MacRae / Collin T McManus / Damian C Ekiert / Gira Bhabha / |
PubMed Abstract | 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 ...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. |
External links | Cell / PubMed:32359438 / PubMed Central |
Methods | EM (single particle) / X-ray diffraction |
Resolution | 2.15 - 3.78 Å |
Structure data | EMDB-20993: Lipophilic Envelope-spanning Tunnel B (LetB), Map 1 EMDB-20994: Lipophilic Envelope-spanning Tunnel B (LetB), Map 2 EMDB-20995: Lipophilic Envelope-spanning Tunnel B (LetB), Map 3 EMDB-20996: Lipophilic Envelope-spanning Tunnel B (LetB), Map 4 EMDB-20997: Lipophilic Envelope-spanning Tunnel B (LetB), Map 5 EMDB-20998: Lipophilic Envelope-spanning Tunnel B (LetB), Map 6 EMDB-20999: Lipophilic Envelope-spanning Tunnel B (LetB), Map 7 EMDB-21000: Lipophilic Envelope-spanning Tunnel B (LetB), Map 8 PDB-6vci: |
Chemicals | ChemComp-HOH: |
Source |
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Keywords | LIPID TRANSPORT / bacterial cell envelope / MCE / YebT / conformational dynamics / LetB |