Dissociation and Reassembly of Escherichia coli Outer Membrane and of Lipopolysaccharide, and Their Reassembly onto Flagellar Basal Bodies

Abstract

Purified lipopolysaccharide vesicles dissociate when treated with ethylenediaminetetraacetic acid (EDTA) and then reassemble when dialyzed against Mg²⁺. Purified outer, lipopolysaccharide membrane (L membrane) is partially dissociated by treatment with EDTA and fully dissociated upon further treatment with Triton X-100. Both the partially and fully dissociated L membrane can be reassembled by dialysis against Mg²⁺. Reassembly of lipopolysaccharide or L membrane in the presence of intact flagella results in specific attachment of flagellar basal bodies to vesicles via the L and sometimes the M ring. Lipopolysaccharide and L membrane appear to be composed of substructures bound together by both Mg²⁺ (divalent cation)-mediated and hydrophobic bonds.