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Inhibition of bacterial conjugation by phage M13 and its protein g3p: quantitative analysis and model.

Lin A, Jimenez J, Derr J, Vera P, Manapat ML, Esvelt KM, Villanueva L, Liu DR, Chen IA - PLoS ONE (2011)

Bottom Line: Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances.We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration.Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage), these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes.

View Article: PubMed Central - PubMed

Affiliation: FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts, United States of America.

ABSTRACT
Conjugation is the main mode of horizontal gene transfer that spreads antibiotic resistance among bacteria. Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances. Filamentous bacteriophages were first observed to inhibit conjugation several decades ago. Here we investigate the mechanism of inhibition and find that the primary effect on conjugation is occlusion of the conjugative pilus by phage particles. This interaction is mediated primarily by phage coat protein g3p, and exogenous addition of the soluble fragment of g3p inhibited conjugation at low nanomolar concentrations. Our data are quantitatively consistent with a simple model in which association between the pili and phage particles or g3p prevents transmission of an F plasmid encoding tetracycline resistance. We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration. Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage), these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes.

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Conjugation without phage: Fraction of F+ cells that are transconjugants over time in the absence of phage.The line is a fit to the model of conjugation (kc = 0.42 /hr, t0 = 0.02 hr, RMSD = 0.05). Data were pooled from several independent replicates.
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pone-0019991-g001: Conjugation without phage: Fraction of F+ cells that are transconjugants over time in the absence of phage.The line is a fit to the model of conjugation (kc = 0.42 /hr, t0 = 0.02 hr, RMSD = 0.05). Data were pooled from several independent replicates.

Mentions: To determine the rate of conjugation, we mixed F+ cells (TOP10F′; F′[lacIq Tn10(tetR)]) expressing CFP (cyan fluorescent protein) with a large excess of F− cells (TOP10) expressing eYFP (enhanced yellow fluorescent protein). We followed the appearance of transconjugants over time during exponential growth in liquid culture as the transconjugant fraction (i.e., fraction of F+ cells exhibiting yellow fluorescence). Without phage, this fraction began at 0 after mixing and approached 1 during the course of the experiment due to the large excess of F− cells (Figure 1).


Inhibition of bacterial conjugation by phage M13 and its protein g3p: quantitative analysis and model.

Lin A, Jimenez J, Derr J, Vera P, Manapat ML, Esvelt KM, Villanueva L, Liu DR, Chen IA - PLoS ONE (2011)

Conjugation without phage: Fraction of F+ cells that are transconjugants over time in the absence of phage.The line is a fit to the model of conjugation (kc = 0.42 /hr, t0 = 0.02 hr, RMSD = 0.05). Data were pooled from several independent replicates.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3102678&req=5

pone-0019991-g001: Conjugation without phage: Fraction of F+ cells that are transconjugants over time in the absence of phage.The line is a fit to the model of conjugation (kc = 0.42 /hr, t0 = 0.02 hr, RMSD = 0.05). Data were pooled from several independent replicates.
Mentions: To determine the rate of conjugation, we mixed F+ cells (TOP10F′; F′[lacIq Tn10(tetR)]) expressing CFP (cyan fluorescent protein) with a large excess of F− cells (TOP10) expressing eYFP (enhanced yellow fluorescent protein). We followed the appearance of transconjugants over time during exponential growth in liquid culture as the transconjugant fraction (i.e., fraction of F+ cells exhibiting yellow fluorescence). Without phage, this fraction began at 0 after mixing and approached 1 during the course of the experiment due to the large excess of F− cells (Figure 1).

Bottom Line: Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances.We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration.Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage), these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes.

View Article: PubMed Central - PubMed

Affiliation: FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts, United States of America.

ABSTRACT
Conjugation is the main mode of horizontal gene transfer that spreads antibiotic resistance among bacteria. Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances. Filamentous bacteriophages were first observed to inhibit conjugation several decades ago. Here we investigate the mechanism of inhibition and find that the primary effect on conjugation is occlusion of the conjugative pilus by phage particles. This interaction is mediated primarily by phage coat protein g3p, and exogenous addition of the soluble fragment of g3p inhibited conjugation at low nanomolar concentrations. Our data are quantitatively consistent with a simple model in which association between the pili and phage particles or g3p prevents transmission of an F plasmid encoding tetracycline resistance. We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration. Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage), these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes.

Show MeSH
Related in: MedlinePlus