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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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Lytic development, assessed in one-step-growth experiments, of bacteriophages λ (a, b) and ϕ24B (c) in the E. coli MG1655 host bearing different plasmids. Symbols in diagrams denote host cells which bear following plasmids: a pJW0tet (closed squares), pGAW3775tet (open squares); b pJW0tet (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles), pJWea22ea8.5 (open triangles); c pJW0tet (closed squares), pSBe.x.r.ϕ24B (open squares). 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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Fig3: Lytic development, assessed in one-step-growth experiments, of bacteriophages λ (a, b) and ϕ24B (c) in the E. coli MG1655 host bearing different plasmids. Symbols in diagrams denote host cells which bear following plasmids: a pJW0tet (closed squares), pGAW3775tet (open squares); b pJW0tet (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles), pJWea22ea8.5 (open triangles); c pJW0tet (closed squares), pSBe.x.r.ϕ24B (open squares). 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: To test potential effects of the exo–xis region on lytic development of phage ϕ24B, we have measured efficiency of adsorption of the phage on host cells and kinetics of phage progeny formation in the presence and absence of the exo–xis region on a multicopy plasmid. We found that neither adsorption of ϕ24B on E. coli cells nor its intracellular lytic development (assessed by measurement of burst size) was affected by the presence of the pSBe.x.r.ϕ24B plasmid (Figs. 2, 3c, respectively). These results were analogous to those reported previously for bacteriophage λ (Łoś et al. 2008a). Interestingly, while the exo–xis region of bacteriophage λ was reported to enhance survival of E. coli cells in cultures infected with λ (Łoś et al. 2008a), an opposite effect was observed when bacteria bearing the pSBe.x.r.ϕ24B plasmid were infected with phage ϕ24B, i.e., lower number of cells survived relative to the strain bearing the plasmid vector (Table 3).Fig. 2


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)

Lytic development, assessed in one-step-growth experiments, of bacteriophages λ (a, b) and ϕ24B (c) in the E. coli MG1655 host bearing different plasmids. Symbols in diagrams denote host cells which bear following plasmids: a pJW0tet (closed squares), pGAW3775tet (open squares); b pJW0tet (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles), pJWea22ea8.5 (open triangles); c pJW0tet (closed squares), pSBe.x.r.ϕ24B (open squares). 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

Fig3: Lytic development, assessed in one-step-growth experiments, of bacteriophages λ (a, b) and ϕ24B (c) in the E. coli MG1655 host bearing different plasmids. Symbols in diagrams denote host cells which bear following plasmids: a pJW0tet (closed squares), pGAW3775tet (open squares); b pJW0tet (closed squares), pGAW3775tet (open squares), pJWea8.5 (open diamonds), pJWea22 (closed triangles), pJWorf (open circles), pJWorfea22 (closed circles), pJWea22ea8.5 (open triangles); c pJW0tet (closed squares), pSBe.x.r.ϕ24B (open squares). 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: To test potential effects of the exo–xis region on lytic development of phage ϕ24B, we have measured efficiency of adsorption of the phage on host cells and kinetics of phage progeny formation in the presence and absence of the exo–xis region on a multicopy plasmid. We found that neither adsorption of ϕ24B on E. coli cells nor its intracellular lytic development (assessed by measurement of burst size) was affected by the presence of the pSBe.x.r.ϕ24B plasmid (Figs. 2, 3c, respectively). These results were analogous to those reported previously for bacteriophage λ (Łoś et al. 2008a). Interestingly, while the exo–xis region of bacteriophage λ was reported to enhance survival of E. coli cells in cultures infected with λ (Łoś et al. 2008a), an opposite effect was observed when bacteria bearing the pSBe.x.r.ϕ24B plasmid were infected with phage ϕ24B, i.e., lower number of cells survived relative to the strain bearing the plasmid vector (Table 3).Fig. 2

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