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Genes from the exo-xis region of λ and Shiga toxin-converting bacteriophages influence lysogenization and prophage induction.

Bloch S, Nejman-Faleńczyk B, Łoś JM, Barańska S, Łepek K, Felczykowska A, Łoś M, Węgrzyn G, Węgrzyn A - Arch. Microbiol. (2013)

Bottom Line: The exo-xis region, present in genomes of lambdoid bacteriophages, contains highly conserved genes of largely unknown functions.No significant effects of an increased copy number of genes located between exo and xis on both efficiency of adsorption on the host cells and lytic development inside the host cell of these bacteriophages were found.We conclude that genes from the exo-xis region of lambdoid bacteriophages participate in the regulation of lysogenization and prophage maintenance.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland.

ABSTRACT
The exo-xis region, present in genomes of lambdoid bacteriophages, contains highly conserved genes of largely unknown functions. In this report, using bacteriophage λ and Shiga toxin-converting bacteriophage ϕ24Β, we demonstrate that the presence of this region on a multicopy plasmid results in impaired lysogenization of Escherichia coli and delayed, while more effective, induction of prophages following stimulation by various agents (mitomycin C, hydrogen peroxide, UV irradiation). Spontaneous induction of λ and ϕ24Β prophages was also more efficient in bacteria carrying additional copies of the corresponding exo-xis region on plasmids. No significant effects of an increased copy number of genes located between exo and xis on both efficiency of adsorption on the host cells and lytic development inside the host cell of these bacteriophages were found. We conclude that genes from the exo-xis region of lambdoid bacteriophages participate in the regulation of lysogenization and prophage maintenance.

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Induction of prophage λ in MG1655 hosts bearing the pJW0tet vector (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles) or pJWea22ea8.5 (open triangles). Bacterial cultures were treated with 0.2 μg/ml mitomycin C (a), 50 J/m2 UV irradiation (b), or 1 mM H2O2 (c) at time 0. Results are shown as PFU (plaque forming units) per cell. The presented results are mean values from three experiments. SD was below 20 % for each point, and is not shown for clarity of presentation
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Fig5: Induction of prophage λ in MG1655 hosts bearing the pJW0tet vector (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles) or pJWea22ea8.5 (open triangles). Bacterial cultures were treated with 0.2 μg/ml mitomycin C (a), 50 J/m2 UV irradiation (b), or 1 mM H2O2 (c) at time 0. Results are shown as PFU (plaque forming units) per cell. The presented results are mean values from three experiments. SD was below 20 % for each point, and is not shown for clarity of presentation

Mentions: We found that induction of the ϕ24B prophage was delayed by 30–60 min in the presence of the exo–xis region on a multicopy plasmid, but this process was finally more efficient than that in control experiments, as more progeny phages were produced (Fig. 4). This phenomenon occurred irrespective of the kind of the inducer used, nevertheless, the delay in prophage induction was the longest (60 min) in experiments with mitomycin C (Fig. 4). Contrary to ϕ24B, effects of the exo–xis region on λ prophage induction depended on the nature of the inducing agent. The presence of the pGAW3775tet plasmid had no effect relative to the vector when mitomycin C was used, delayed the induction in the presence of hydrogen peroxide, and caused earlier induction after UV irradiation (Fig. 4). Nevertheless, with exception of the induction with mitomycin C, final efficiency of induction of λ prophage was higher in the presence of the exo–xis region on a plasmid relative to control experiments (Fig. 4). When particular genes or combinations of two or a few genes from the λ exo–xis region were present on the plasmid, their effect on λ prophage induction was generally less pronounced than that of the whole region (Fig. 5).Fig. 4


Genes from the exo-xis region of λ and Shiga toxin-converting bacteriophages influence lysogenization and prophage induction.

Bloch S, Nejman-Faleńczyk B, Łoś JM, Barańska S, Łepek K, Felczykowska A, Łoś M, Węgrzyn G, Węgrzyn A - Arch. Microbiol. (2013)

Induction of prophage λ in MG1655 hosts bearing the pJW0tet vector (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles) or pJWea22ea8.5 (open triangles). Bacterial cultures were treated with 0.2 μg/ml mitomycin C (a), 50 J/m2 UV irradiation (b), or 1 mM H2O2 (c) at time 0. Results are shown as PFU (plaque forming units) per cell. The presented results are mean values from three experiments. SD was below 20 % for each point, and is not shown for clarity of presentation
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3824215&req=5

Fig5: Induction of prophage λ in MG1655 hosts bearing the pJW0tet vector (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles) or pJWea22ea8.5 (open triangles). Bacterial cultures were treated with 0.2 μg/ml mitomycin C (a), 50 J/m2 UV irradiation (b), or 1 mM H2O2 (c) at time 0. Results are shown as PFU (plaque forming units) per cell. The presented results are mean values from three experiments. SD was below 20 % for each point, and is not shown for clarity of presentation
Mentions: We found that induction of the ϕ24B prophage was delayed by 30–60 min in the presence of the exo–xis region on a multicopy plasmid, but this process was finally more efficient than that in control experiments, as more progeny phages were produced (Fig. 4). This phenomenon occurred irrespective of the kind of the inducer used, nevertheless, the delay in prophage induction was the longest (60 min) in experiments with mitomycin C (Fig. 4). Contrary to ϕ24B, effects of the exo–xis region on λ prophage induction depended on the nature of the inducing agent. The presence of the pGAW3775tet plasmid had no effect relative to the vector when mitomycin C was used, delayed the induction in the presence of hydrogen peroxide, and caused earlier induction after UV irradiation (Fig. 4). Nevertheless, with exception of the induction with mitomycin C, final efficiency of induction of λ prophage was higher in the presence of the exo–xis region on a plasmid relative to control experiments (Fig. 4). When particular genes or combinations of two or a few genes from the λ exo–xis region were present on the plasmid, their effect on λ prophage induction was generally less pronounced than that of the whole region (Fig. 5).Fig. 4

Bottom Line: The exo-xis region, present in genomes of lambdoid bacteriophages, contains highly conserved genes of largely unknown functions.No significant effects of an increased copy number of genes located between exo and xis on both efficiency of adsorption on the host cells and lytic development inside the host cell of these bacteriophages were found.We conclude that genes from the exo-xis region of lambdoid bacteriophages participate in the regulation of lysogenization and prophage maintenance.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland.

ABSTRACT
The exo-xis region, present in genomes of lambdoid bacteriophages, contains highly conserved genes of largely unknown functions. In this report, using bacteriophage λ and Shiga toxin-converting bacteriophage ϕ24Β, we demonstrate that the presence of this region on a multicopy plasmid results in impaired lysogenization of Escherichia coli and delayed, while more effective, induction of prophages following stimulation by various agents (mitomycin C, hydrogen peroxide, UV irradiation). Spontaneous induction of λ and ϕ24Β prophages was also more efficient in bacteria carrying additional copies of the corresponding exo-xis region on plasmids. No significant effects of an increased copy number of genes located between exo and xis on both efficiency of adsorption on the host cells and lytic development inside the host cell of these bacteriophages were found. We conclude that genes from the exo-xis region of lambdoid bacteriophages participate in the regulation of lysogenization and prophage maintenance.

Show MeSH
Related in: MedlinePlus