Lysogeny phage

Lysogeny is generally a veiy stable state, but occasionally a cell will lose its prophage and these cured cells are once more susceptible to infection by that particular phage type. 

The Dormant Prophage State of A Is Maintained by a Phage-Encoded Repressor Events That Follow Infection of Escherichia coli by Bacteriophage A Can Lead to Lysis or Lysogeny The N Protein Is an Antiterminator That Results in Extension of Early Transcripts Another Antiterminator, the Q Protein, Is the Key to Late Transcription... 

Bacteriophages Bacteriophages (or phages) adsorb to the bacterial host cell and then inject the DNA genome into the cell, leaving the protein capsid outside. Two alternative modes of infection may follow lytic infection or lysogeny (Fig. 1). 

FIGURE 7.1 A bipartite graph in which circles represent interactions and rectangles represent biomolecules. This example is a modified Petri net modeling the phage X lysis-lysogeny circuit [Matsuno et al. 2000],... 

In a study of the establishment of lysogeny in E. coli strain C by phage P2, it was found that treatment of infect cells with 5-hydroxyuridine increases the frequency of lysogenisation [18]. The selective inhibition of protein synthesis in infected cells tends to favour the lysogenic response over the lytic [18]. 

Temperate phages Bacterial phages that can establish a condition of lysogeny. 

Induction of Lysogeny. As outlined, the growth of phage from lysogenic bacteria is induced by agents which interact with DNA. 

Three loci of the recombination system, two loci of integration, one locus of bacterial metabolic suppression, two loci of duplication, and the Cn and Cm loci which control the selection of developmental pathways (lytic growth vs lysogeny) begin to function within the first 5-7 min. Transcription of the late loci is possible only after circularization of the phage DNA. This conversion of DNA structure, as mentioned above, occurs very early and requires the aid of bacterial ligase. 

With lysogeny, rapid transcription is initiated in the Cj region. Increasing concentrations of Cl protein repressor turns off transcription in all operons involved with lysis. At the same time, the loci which determine lysogeny and are involved in incorporation of the phage DNA into the bacterial chromosome are transcribed. Ultimately, however, only the small region of DNA containing the C] locus remains active. 

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