Enterobacteria phage T2

Enterobacteria phage T2
Virus classification
Group:	Group I (dsDNA)
Order:	Caudovirales
Family:	Myoviridae
Genus:	T4-like viruses
Species:	Enterobacteria phage T2

Enterobacteria phage T2 is a virus that infects and kills E. coli. It is in the genus T4-like viruses, and the family Myoviridae. Its genome consists of linear double-stranded DNA, with repeats at either end. The phage is covered by a protective protein coat.

The T2 phage can quickly turn an E. coli cell into a T2-producing factory that releases phages when the cell ruptures. Experiments conducted by Alfred Hershey and Martha Chase demonstrated how the DNA of viruses is injected into the bacterial cells, while most of the viral proteins remain outside. The injected DNA molecules cause the bacterial cells to produce more viral DNA and proteins. These discoveries supported that DNA, rather than proteins, is the hereditary material.

The first phages that were studied in detail included seven that commonly infect E. coli. They were named Type 1 (T1), Type 2 (T2), etc., for easy reference, but as it happens T2, T4 and T6 are structurally similar (polyhedral head, tail structure and fibres for attaching to the surface of a bacterium), and this easily recognizable shape is now referred to as the T-Even phage.

The phage can attach to the surface of a bacterium using the proteins on its 'feet' (tail fibres), and inject its genetic material (either, but not both, DNA or RNA). This genetic material uses the host cell's ribosomes to replicate, and synthesise proteins for the capsid and tail of the phage. New phages are assembled within the cell - up to 200 - until the cellular membrane lyses (splits open). The newly made phages are now free to attack more cells. This is the Lytic cycle.