Prophage


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prophage

[′prō‚fāj]
(virology)
Integrated unit formed by union of the provirus into the bacterial genome.

Prophage

 

a latent, or occult, noninfectious form of temperate bacteriophage that is present in lysogenic bacteria.

Prophage is the deoxyribonucleic acid (DNA) of a temperate bacteriophage combined with the DNA of a lysogenized bacterium. The DNA of a prophage is approximately 1/50 to 1/100 the size of the DNA of a bacterial chromosome and contains about 105 pairs of nucleotides. Thus, a prophage is a complete genome of a phage and contains about 100 genes.

A prophage generally occupies a specific locus in a bacterial chromosome and is inherited like ordinary bacterial genes. The prophage of a λ-phage, for example, is localized in a chromosome of colibacillus together with the gene that controls the splitting of galactose. The location of a prophage is genetically controlled by its special region, which constitutes about 1/15 of the total length of the genome.

A prophage is nonpathogenic for a bacterial cell and is replicated over many generations simultaneously with the bacterial chromosome. However, in some growing lysogenic bacteria (approximately one cell per million), the prophage becomes infectious, that is, it becomes induced. As a result of induction, it is converted into an intracellular vegetative phage that is not bound to the bacterial chromosome. When this type of phage replicates, the bacterial cell undergoes lysis and dies. Individual lysogenic bacteria may carry several prophages.

A. V. KOLOBOV

References in periodicals archive ?
We uploaded assembled data from the strains in FASTA file format to the PHAge Search Tool (PHAST) web server for prophage identification (22).
2011) CRISPR Inhibition of Prophage Acquisition in Streptococcus pyogenes.
aureus carrying virulence and antibiotic resistance genes on mobile genetic elements such as plasmids, prophages, and staphylococcal pathogenic islands (SaPIs), and these can horizontally transfer between strains.
Typhimurium it has been observed that the T3S effector protein SopE is encoded by a prophage [131].
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In addition, the fur mutation displayed an increased synthesis of PBSX defective prophage encoded proteins.
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7] Rice SA, Tan CH, Mikkelsen PJ, Kung V, Woo J, Tay M, Hauser A, McDougald D, Webb JS, Kjelleberg S The biofilm life cycle and virulence of Pseudomonas aeruginosa are dependent on a filamentous prophage.
The BGI researchers found that the Shiga-toxin-encoding genes, responsible for most of the pathogenicity of the disease, were likely encoded by a viral prophage that integrated in the bacterial chromosome.
These isolates carried different combinations of alleles of tcpA and CTX prophage repressor gene (rstR) (4).