The Assembly of a Major Outer Membrane Protein (OmpF) in the Cell Surface of Escherichia coli

Abstract

Escherichia coli OmpF protein of the outer membrane behaved essentially the same as the OmpC protein on reconstitution of the cell surface. An ordered hexagonal lattice structure was reconstituted on the entire surface of the lipoprotein-bearing peptidoglycan sacculus from the OmpF protein and lipopolysaccharide. With the lipoprotein-free peptidoglycan sacculus, the hexagonal lattice structure was formed independently of the sacculus. In the absence of the peptidoglycan, the OmpF protein and lipopolysaccharide were assembled into a vesicle with an ordered hexagonal lattice. The role of lipopolysaccharide in lattice formation was taken over by lipid A or even by fatty acid. However, the lattice constant with these lipopolysaccharide derivatives was appreciably smaller than that with the wild-type lipopolysaccharide. The importance of the lipoprotein in the interaction between the outer membrane and the peptidoglycan layer was also shown by using a lipoprotein-negative mutant.