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Publication Abstract from PubMed

MsbA is an essential ATP-binding cassette transporter in Gram-negative bacteria that transports lipid A and lipopolysaccharide from the cytoplasmic leaflet to the periplasmic leaflet of the inner membrane. Here we report the X-ray structure of MsbA from Salmonella typhimurium at 2.8-A resolution in an inward-facing conformation after cocrystallization with lipid A and using a stabilizing facial amphiphile. The structure displays a large amplitude opening in the transmembrane portal, which is likely required for lipid A to pass from its site of synthesis into the protein-enclosed transport pathway. Putative lipid A density is observed further inside the transmembrane cavity, consistent with a trap and flip model. Additional electron density attributed to lipid A is observed near an outer surface cleft at the periplasmic ends of the transmembrane helices. These findings provide new structural insights into the lipid A transport pathway through comparative analysis with existing MsbA structures.

Structural Insights into the Lipid A Transport Pathway in MsbA.,Padayatti PS, Lee SC, Stanfield RL, Wen PC, Tajkhorshid E, Wilson IA, Zhang Q Structure. 2019 Apr 25. pii: S0969-2126(19)30129-7. doi:, 10.1016/j.str.2019.04.007. PMID:31130486^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.