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Conjugative DNA transfer induces the bacterial SOS response and promotes antibiotic resistance development through integron activation.

Baharoglu Z, Bikard D, Mazel D - PLoS Genet. (2010)

Bottom Line: We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements.Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell.Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France.

ABSTRACT
Conjugation is one mechanism for intra- and inter-species horizontal gene transfer among bacteria. Conjugative elements have been instrumental in many bacterial species to face the threat of antibiotics, by allowing them to evolve and adapt to these hostile conditions. Conjugative plasmids are transferred to plasmidless recipient cells as single-stranded DNA. We used lacZ and gfp fusions to address whether conjugation induces the SOS response and the integron integrase. The SOS response controls a series of genes responsible for DNA damage repair, which can lead to recombination and mutagenesis. In this manuscript, we show that conjugative transfer of ssDNA induces the bacterial SOS stress response, unless an anti-SOS factor is present to alleviate this response. We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements. Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell. Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria.

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Conjugation induces SOS in E. coli and V. cholerae.Shaded bars: E. coli. Dotted bars: V. cholerae. Grey: values at peak of induction t40-t60min (for SXT, the peak is shown at t210); White: values at t240. A: conjugation rates in E. coli recA+ and recA (strains 7651 and 7713) and V. cholerae (7453); B: SOS induction in total population of recipient E. coli and V. cholerae measured by β-gal tests; C: SOS induction ratio in conjugants only, for E. coli and V. cholerae. Induction was calculated as described in Materials and Methods. Induction ratios are units at time tx/units at time t0.
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pgen-1001165-g001: Conjugation induces SOS in E. coli and V. cholerae.Shaded bars: E. coli. Dotted bars: V. cholerae. Grey: values at peak of induction t40-t60min (for SXT, the peak is shown at t210); White: values at t240. A: conjugation rates in E. coli recA+ and recA (strains 7651 and 7713) and V. cholerae (7453); B: SOS induction in total population of recipient E. coli and V. cholerae measured by β-gal tests; C: SOS induction ratio in conjugants only, for E. coli and V. cholerae. Induction was calculated as described in Materials and Methods. Induction ratios are units at time tx/units at time t0.

Mentions: The conjugation rates of these plasmids were first measured at various time points after donor and recipient cells were mixed (Figure 1A). In E. coli, all plasmids conjugate approximately at the same rate so that nearly all recipients have received a plasmid after 60 min of conjugation. In V. cholerae transfer rates vary considerably, only 1 in 105 cells have received a plasmid after 4h of mating with R6Kdrd and R388, while RP4 has a transfer rate similar to that of E. coli (10−1 to 1). Neither R64drd nor R100-1 replicate in V. cholerae. In order to address whether R100-1 actually transfers from E. coli into V. cholerae, we used pSU19-oriTF plasmids containing the oriTF (72 bp) of plasmid F. Plasmid F does not replicate in V. cholerae and oriTF is 98% identical to oriTR100. The high oriTF transfer rate observed at 1h of mating confirms that plasmids F and R100-1 (and presumably R64drd) can indeed transfer into V. cholerae and that the lack of R100/R64 transconjugants is due to their inability to establish themselves in this bacterium.


Conjugative DNA transfer induces the bacterial SOS response and promotes antibiotic resistance development through integron activation.

Baharoglu Z, Bikard D, Mazel D - PLoS Genet. (2010)

Conjugation induces SOS in E. coli and V. cholerae.Shaded bars: E. coli. Dotted bars: V. cholerae. Grey: values at peak of induction t40-t60min (for SXT, the peak is shown at t210); White: values at t240. A: conjugation rates in E. coli recA+ and recA (strains 7651 and 7713) and V. cholerae (7453); B: SOS induction in total population of recipient E. coli and V. cholerae measured by β-gal tests; C: SOS induction ratio in conjugants only, for E. coli and V. cholerae. Induction was calculated as described in Materials and Methods. Induction ratios are units at time tx/units at time t0.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2958807&req=5

pgen-1001165-g001: Conjugation induces SOS in E. coli and V. cholerae.Shaded bars: E. coli. Dotted bars: V. cholerae. Grey: values at peak of induction t40-t60min (for SXT, the peak is shown at t210); White: values at t240. A: conjugation rates in E. coli recA+ and recA (strains 7651 and 7713) and V. cholerae (7453); B: SOS induction in total population of recipient E. coli and V. cholerae measured by β-gal tests; C: SOS induction ratio in conjugants only, for E. coli and V. cholerae. Induction was calculated as described in Materials and Methods. Induction ratios are units at time tx/units at time t0.
Mentions: The conjugation rates of these plasmids were first measured at various time points after donor and recipient cells were mixed (Figure 1A). In E. coli, all plasmids conjugate approximately at the same rate so that nearly all recipients have received a plasmid after 60 min of conjugation. In V. cholerae transfer rates vary considerably, only 1 in 105 cells have received a plasmid after 4h of mating with R6Kdrd and R388, while RP4 has a transfer rate similar to that of E. coli (10−1 to 1). Neither R64drd nor R100-1 replicate in V. cholerae. In order to address whether R100-1 actually transfers from E. coli into V. cholerae, we used pSU19-oriTF plasmids containing the oriTF (72 bp) of plasmid F. Plasmid F does not replicate in V. cholerae and oriTF is 98% identical to oriTR100. The high oriTF transfer rate observed at 1h of mating confirms that plasmids F and R100-1 (and presumably R64drd) can indeed transfer into V. cholerae and that the lack of R100/R64 transconjugants is due to their inability to establish themselves in this bacterium.

Bottom Line: We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements.Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell.Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France.

ABSTRACT
Conjugation is one mechanism for intra- and inter-species horizontal gene transfer among bacteria. Conjugative elements have been instrumental in many bacterial species to face the threat of antibiotics, by allowing them to evolve and adapt to these hostile conditions. Conjugative plasmids are transferred to plasmidless recipient cells as single-stranded DNA. We used lacZ and gfp fusions to address whether conjugation induces the SOS response and the integron integrase. The SOS response controls a series of genes responsible for DNA damage repair, which can lead to recombination and mutagenesis. In this manuscript, we show that conjugative transfer of ssDNA induces the bacterial SOS stress response, unless an anti-SOS factor is present to alleviate this response. We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements. Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell. Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria.

Show MeSH
Related in: MedlinePlus