Accelerated Adsorption of Bacteriophage T5 to Escherichia coli F, Resulting from Reversible Tail Fiber-Lipopolysaccharide Binding

Abstract

A dual specificity for phage T5 adsorption to Escherichia coli cells is shown. The tail fiber-containing phages T5 + and mutant hd-3 adsorbed rapidly to E. coli F (1.2 × 10 −9 ml min −1 ), whereas the adsorption rate of the tail fiber-less mutants hd-1, hd-2, and hd-4 was low (7 × 10 −11 ml min −1 ). The differences in adsorption rates were due to the particular lipopolysaccharide structure of E. coli F. Phage T4-resistant mutants of E. coli F with an altered lipopolysaccharide structure exhibited similar low adsorption for all phage strains with and without tail fibers. The same held true for E. coli K-12 and B which also differ from E. coli F in their lipopolysaccharide structures. Only the tail fiber-containing phages reversibly bound to isolated lipopolysaccharides of E. coli F. Infection by all phage strains strictly depended on the tonA -coded protein in the outer membrane of E. coli . We assume that the reversible preadsorption by the tail fibers to lipopolysaccharide accelerates infection which occurs via the highly specific irreversible binding of the phage tail to the tonA -coded protein receptor. The difference between rapid and slow adsorption was also revealed by the competition between ferrichrome and T5 for binding to their common tonA -coded receptor in tonB strains of E. coli . Whereas binding of T5 + to E. coli K-12 and of the tail-fiber-less mutant hd-2 to E. coli F and K-12 was inhibited 50% by about 0.01 μM ferrichrome, adsorption of T5 to E. coli F was inhibited only 40% by even 1,000-fold higher ferrichrome concentrations.