The short tail of Podoviridae acts as a molecular machine that ejects the viral DNA from the capsid into the host cell cytoplasm. The ejection system consists of a central tube, the connector which attaches the tail to the phage capsid and released inner core proteins.
Upon binding to the host cell surface, podoviruses display a tube-like extension of their short tail that penetrates both host membranes. This tail extension comes from the release of viral core proteins with channel forming properties .
The source of the forces that drive viral genome ejection is probably in part due to osmotic pressure imbalance between the virus inside and the host cytoplasm .
Gram(-) hosts:
- Attachment to a host cell outer membrane (OM) receptor.
- Ejection proteins in the head form a channel that penetrates the OM. Virion-associated exolysin (if present) hydrolyzes the peptidoglycan layer.
- Channel extends through the inner membrane (IM). Some viruses may use an IM receptor.
- Viral DNA translocation into the host cytoplasm.
Gram(+) hosts:
- Attachment to a host cell wall receptor.
- Virion-associated exolysin (if present)hydrolyzes the peptidoglycan layer.
- ? Channel formation or tunneling of a way through the host cell wall ?
- Viral DNA translocation into the host cytoplasm.