Enterobacteria phage T4

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Enterobacteria phage T4
Structural overview of the T4 phage
Virus classification
Group: Group I (dsDNA)
Order: Caudovirales
Family: Myoviridae
Genus: T4-like viruses
Species: T4 Phage

Enterobacteria phage T4 is a bacteriophage that infects E. coli bacteria. Its DNA is 169–170 kbp long, and is held in an icosahedral head. T4 is a relatively large phage, at approximately 90 nm wide and 200 nm long (most phages range from 25 to 200 nm in length). Its tail fibres allow attachment to a host cell, and the T4’s tail is hollow so that it can pass its nucleic acid to the cell it is infecting during attachment. T4 is capable of undergoing only a lytic lifecycle and not the lysogenic lifecycle.

Contents

[edit] Tail fibers

Tail fibers participate in the reversible bonding of the phage to the cellular surface of the bacteria. They are also important in recognizing the receptors and if the bacterium fits in the host range.

[edit] Infection process

The T4 Phage initiates infection of an E. coli bacterium by recognizing cell surface receptors of the host with its long tail fibers (LTF). A recognition signal is sent through the LTFs to the baseplate. This unravels the short tail fibers (STF) that bind irreversibly to the E. coli cell surface. The baseplate changes conformation and the tail sheath contracts causing GP5 at the end of the tail tube to puncture the outer membrane of the cell. The lysozyme domain of GP5 is activated and degrades the periplasmic peptidoglycan layer. The remaining part of the membrane is degraded and, DNA from the head of the Phage can travel through the tail tube and enter the E. coli.

[edit] Life cycle

The lytic lifecycle (from entering a bacterium to its destruction) takes approximately 30 minutes (at 37 °C) and consists of:[citation needed]

After the life cycle is complete, the host cell bursts open and ejects the newly built viruses into the environment, destroying the host cell. T4 has a burst size of approximately 100-150 viral particles per infected host. Complementation, deletion, and recombination tests can be used to map out the rII gene locus by using T4. These bacteriophage infect a host cell with their information and then blow up the host cell, thereby propagating themselves.

[edit] Features

The T4 phage has some unique features, such as:

In addition, a number of Nobel Prize winners worked with phage T4 or T4-like phages including Max Delbrück, Salvador Luria, Alfred Hershey, James D. Watson, and Francis Crick. Other important scientists who worked with phage T4 include Michael Rossmann, Seymour Benzer, Bruce Alberts, Gisela Mosig, Richard Lenski, and James Bull. Click here for a more-complete list of phage workers.

[edit] See also

[edit] References

  1. ^ Tarahovsky, Y. S.; Ivanitsky, G.R.; Khusainov, A.A. (1994). "Lysis of Escherichia coli cells by bacteriophage T4". FEMS Microbiology Letters 122: 195–200. doi:10.1111/j.1574-6968.1994.tb07164.x. 
  2. ^ Oda, M.; M. Morita, H. Unno, Y. Tanji (2004). "Rapid Detection of Escherichia coli O157: H7 by Using Green Fluorescent Protein-Labeled PP01 Bacteriophage". Applied and Environmental Microbiology 70 (1): 527–534. doi:10.1128/AEM.70.1.527-534.2004. PMC 321238. PMID 14711684. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=321238. 
  3. ^ a b Madigan M, Martinko J (editors) (2006). Brock Biology of Microorganisms (11th ed.). Prentice Hall. ISBN 0-13-144329-1. 

[edit] Further reading

[edit] External links

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