5l75

Publication Abstract from PubMed

The cell surface of most Gram-negative bacteria contains lipopolysaccharide that is essential for their viability and drug resistance. A 134-kDa protein complex LptB2FG is unique among ATP-binding cassette transporters because it extracts lipopolysaccharide from the external leaflet of the inner membrane and propels it along a filament that extends across the periplasm to directly deliver lipopolysaccharide into the external leaflet of the outer membrane. Here we report the crystal structure of the lipopolysaccharide transporter LptB2FG from Klebsiella pneumoniae, in which both LptF and LptG are composed of a beta-jellyroll-like periplasmic domain and six alpha-helical segments in the transmembrane domain. LptF and LptG form a central cavity containing highly conserved hydrophobic residues. Structural and functional studies suggest that LptB2FG uses an alternating lateral access mechanism to extract lipopolysaccharide and traffic it along the hydrophobic cavity toward the transporter's periplasmic domains.Lipopolysaccharides (LPS) are synthesized at the periplasmic side of the inner membrane of Gram-negative bacteria and are then extracted by the LptB2FG complex during the first step of LPS transport to the outer membrane. Here the authors present the LptB2FG structure, which supports an alternating lateral access mechanism for LPS extraction.

Structural and functional insights into the lipopolysaccharide ABC transporter LptB2FG.,Dong H, Zhang Z, Tang X, Paterson NG, Dong C Nat Commun. 2017 Aug 9;8(1):222. doi: 10.1038/s41467-017-00273-5. PMID:28790314^[1]

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