During the infection, T5 attaches to E. coli in a two-step manner: first, by reversible binding to the lipopolysaccharide (LPS) O-antigen mediated by the L-shaped tail fibers, followed by a second, irreversible step, in which the T5-receptor-binding protein (Gp5) binds to the host’s outer membrane iron-ferrichrome transporter FhuA [19,20], leading to a lytic infection cycle. This evidence concerns the gene GP5 and infection.