6mhu | pdb_00006mhu
Nucleotide-free Cryo-EM Structure of E.coli LptB2FG Transporter
Structural highlights
FunctionLPTF_ECOLI Part of the ABC transporter complex LptBFG involved in the translocation of lipopolysaccharide (LPS) from the inner membrane to the outer membrane.[1] Publication Abstract from PubMedIn Gram-negative bacteria, lipopolysaccharide is essential for outer membrane formation and antibiotic resistance. The seven lipopolysaccharide transport (Lpt) proteins A-G move lipopolysaccharide from the inner to the outer membrane. The ATP-binding cassette transporter LptB2FG, which tightly associates with LptC, extracts lipopolysaccharide out of the inner membrane. The mechanism of the LptB2FG-LptC complex (LptB2FGC) and the role of LptC in lipopolysaccharide transport are poorly understood. Here we characterize the structures of LptB2FG and LptB2FGC in nucleotide-free and vanadate-trapped states, using single-particle cryo-electron microscopy. These structures resolve the bound lipopolysaccharide, reveal transporter-lipopolysaccharide interactions with side-chain details and uncover how the capture and extrusion of lipopolysaccharide are coupled to conformational rearrangements of LptB2FGC. LptC inserts its transmembrane helix between the two transmembrane domains of LptB2FG, which represents a previously unknown regulatory mechanism for ATP-binding cassette transporters. Our results suggest a role for LptC in achieving efficient lipopolysaccharide transport, by coordinating the action of LptB2FG in the inner membrane and Lpt protein interactions in the periplasm. Structural basis of lipopolysaccharide extraction by the LptB2FGC complex.,Li Y, Orlando BJ, Liao M Nature. 2019 Mar;567(7749):486-490. doi: 10.1038/s41586-019-1025-6. Epub 2019 Mar, 20. PMID:30894744[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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