Download MendeleyLetB Structure Reveals a Tunnel for Lipid Transport across the Bacterial Envelope.
Isom, G.L., Coudray, N., MacRae, M.R., McManus, C.T., Ekiert, D.C., Bhabha, G.(2020) Cell 181: 653-664.e19
- PubMed: 32359438
- DOI: https://doi.org/10.1016/j.cell.2020.03.030
- Primary Citation of Related Structures:
6V0C, 6V0D, 6V0E, 6V0F, 6V0G, 6V0H, 6V0I, 6V0J, 6VCI - 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 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.
Organizational Affiliation:
Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA.
