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.
Short noncontractile tail machines: adsorption and DNA delivery by podoviruses
Casjens SR, Molineux IJ
Adv Exp Med Biol. 2012;726:143-79
Structural characterization of the bacteriophage T7 tail machinery
Cuervo A, Pulido-Cid M, Chagoyen M, Arranz R, Gonzalez-Garcia VA, Garcia-Doval C, Caston JR, Valpuesta JM, van Raaij MJ, Martin-Benito J, Carrascosa JL
J Biol Chem. 2013 Sep 6;288(36):26290-9
The bacteriophage t7 virion undergoes extensive structural remodeling during infection
Bo Hu, William Margolin, Ian J Molineux, Jun Liu
Science February 1, 2013; 339: 576-579
A conformational switch in bacteriophage p22 portal protein primes genome injection
Hongjin Zheng, Adam S Olia, Melissa Gonen, Simeon Andrews, Gino Cingolani, Tamir Gonen
Mol. Cell February 15, 2008; 29: 376-383
Long noncontractile tail machines of bacteriophages
Alan R Davidson, Lia Cardarelli, Lisa G Pell, Devon R Radford, Karen L Maxwell
Adv. Exp. Med. Biol. 2012; 726: 115-142
