Peptidoglycan (PG) is the primary component of the bacterial cell wall, which is made up of glycan chains cross-linked by peptide side chains to create a continuous, mesh-like structure that surrounds the cytoplasmic membrane. This covalently closed protective barrier primarily aids in maintaining cellular shape and providing structural integrity, but very little is known about how large molecules (like proteins and DNA) are translocated across this essential structure. In the case of bacteriophages (which are viruses that infect bacteria), one strategy has been the incorporation of a peptidoglycan-hydrolase in their virion to ensure their genomic DNA reaches the host cell cytoplasm, but what happens if the bacteriophage does not produce one of these enzymes?
To date, the biology of lambda phage and its infection of Escherichia coli is one of the well-studied, classic model systems in microbiology. It is well known that at the start of the infection, the receptor binding protein J at the tail tip of the virion interacts with the outer membrane lamB protein of the E.coli host for the attachment and release of its genomic DNA. Yet, the last piece of the puzzle is how it translocates DNA across the peptidoglycan layer when there is no peptidoglycan hydrolase.