LptE binds to and alters the physical state of LPS to catalyze its assembly at the cell surface

Significance The outermost membrane of Gram-negative bacteria contains lipopolysaccharide (LPS), and its proper placement on the cell surface is required to establish an effective permeability barrier. The presence of LPS prevents small hydrophobic molecules from entering the cell making it difficult to develop antibiotics. LPS is synthesized inside the cell and must move across three compartments to the cell surface. The final step of LPS transport (Lpt), translocation of LPS across the outer membrane, is accomplished by a two-protein complex (LptDE) that must insert LPS into its outer leaflet. We have identified a binding site within LptE critical for the proper function of the translocon. LptE binds LPS and changes its physical state to facilitate its translocation through the outer membrane.