Regulation of Bacteriophage P22 DNA synthesis and repressor levels in P22cly infections

Tokuno, Shin-Ichi; Gough, Michael

doi:10.1128/jvi.21.3.956-964.1977

Cited by 5 publications

(1 citation statement)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The maintenance of lysogeny in cells carrying the P22 prophage depends on the function of the products encoded by the c2 and mnt genes [20,21], which are in different regions of the P22 genome [22]. The Mnt repressor is involved in regulating the sie (superinfec tion exclusion) gene [23], and a prophage with a sie mutation fails to exclude a superinfecting phage [24]. The VirA (mapping close to or within the mnt locus) and VirB loci are in different regions of the phage P22 genome [21,22].…”

Section: Discussionmentioning

confidence: 99%

Genome instability of Pseudomonas aeruginosa phages of the EL species: Examination of virulent mutants

et al. 2011

View full text Add to dashboard Cite

The article continues a study of pseudolysogeny in Pseudominas aeruginosa infected with phiKZ like phages of the EL species. Analysis was performed for several newly isolated vir mutants of EL phages (EL and RU) that were virulent (capable of causing lysis of bacteria infected with the wild type phage) and a lower extent of opalescence of negative colonies (NCs). Wile type recombinants were detected in crosses of virulent mutants of phages EL and RU to confirm the polygenic control of virulence. Since a deletion mutation was found in one of the virulent EL mutants and high genetic instability was characteristic of another mutant, a mobile genetic element was assumed to play a role in mutagenesis. Pseudolysogeny of bacteria provides for horizontal gene transfer between different bacterial strains. Hence, sequencing of the phage genome and demonstration of the lack of toxic gene products are insufficient for the phage to be included into a therapeu tic mixture. To use live phages, it is essential to study in detail the possible consequences of their interaction with host bacteria.

show abstract

Section: Discussionmentioning

confidence: 99%

Genome instability of Pseudomonas aeruginosa phages of the EL species: Examination of virulent mutants

et al. 2011

View full text Add to dashboard Cite

show abstract

Effect of mutant host RNA polymerase on the bifunctional activities of P22 gene c1

et al. 1977

View full text Add to dashboard Cite

The product of phage P22 gene c1 has two functions: (1) it promotes synthesis of repressor and (2) during the first minutes of infection it retards expression of some lytic genes. We call the second, negative function "c1 retardation". We investigated c1 retardation in a mutant host of Salmonella typhimurium that is resistant to rifampicin and carries an altered RNA polymerase. No c1 retardation of DNA synthesis was detectable in this host after infection with wild-type phages. This elimination of the normally detectable c1 function leads to the conclusion that the mutant RNA polymerase interferes with the expression of c1 gene activity. Wild-type genes form clear plaques on the mutant host. Mutants of P22 called cly were isolated by others. These mutants form turbid plaques on the altered RNA polymerase host. Infections with P22 cly in the mutant host resulted in detectable c1 retardation. The cly mutation therefore restores c1 activity in a host which wild-type c1 is not expressed. Two spontaneous mutants were isolated from the mutant host. These two strains allowed partial expression of c1 retardation, although they remained rifampicin resistant. We interpret our data to indicate that expression of the normal functions of the gene c1 product requires an interaction of that product with the host RNA polymerase.

show abstract

Repressor synthesis in regulatory mutants of bacteriophage P22

Harvey¹,

Heil²,

Prell³

1979

Molec. Gen. Genet.

View full text Add to dashboard Cite

SDS-polyacrylamide gel analysis of P22-infected Salmonella has allowed identification of the c2 repressor (MW 31,000) and study of repressor synthesis in regulatory mutants of P22. Repressor is synthesized in reduced amounts or is absent in infections with P22, clNo.7, P22, c2 am08, P22 c3 am03, and P22 c3 am012, but is synthesized in markedly increased amounts in the virulent mutant, P22 virB3, and its component mutants, vx and k5. Higher levels of repressor are also found in the P22 cly 17 mutant.

show abstract

Regulation of Bacteriophage P22 DNA synthesis and repressor levels in P22cly infections

Cited by 5 publications

References 14 publications

Genome instability of Pseudomonas aeruginosa phages of the EL species: Examination of virulent mutants

Genome instability of Pseudomonas aeruginosa phages of the EL species: Examination of virulent mutants

Effect of mutant host RNA polymerase on the bifunctional activities of P22 gene c1

Repressor synthesis in regulatory mutants of bacteriophage P22

Contact Info

Product

Resources

About