Phage proteins can modify bacterial surface structures, especially O-antigens, to facilitate infection, even though these structures typically act as barriers.

Some phages encode proteins that alter or modify O-antigens without known seroconversion enzymes, helping them bypass bacterial defenses.

Researchers have identified a novel Type IV restriction enzyme system in E. coli that involves two GmrS-like genes and can be inhibited by specific phage proteins.

The study reveals how bacteriophages overcome bacterial defense mechanisms, showcasing new functions of injected phage proteins.

Internal phage proteins Ip1, Ip2, and Ip3 can inhibit bacterial restriction enzymes like GmrSD, which target phage DNA modifications.

Disruption of bacterial surface polysaccharides and restriction enzymes enhances phage infectivity, illustrating layered bacterial immune defenses.

Phages have evolved multiple strategies, including surface modifications and direct enzyme inhibition, to bypass bacterial immune systems.

Diverse phage accessory genes can antagonize core bacterial pathways such as O-antigen biosynthesis and restriction-modification systems.