LetB Structure Reveals a Tunnel for Lipid Transport across the Bacterial Envelope.
Cell
; 181(3): 653-664.e19, 2020 04 30.
Article
em En
| MEDLINE
| ID: mdl-32359438
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 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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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
/
Proteínas de Bactérias
/
Lipopolissacarídeos
Idioma:
En
Revista:
Cell
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Estados Unidos