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Control of directionality in bacteriophage mv4 site-specific recombination: functional analysis of the Xis factor

Michèle Coddeville1, Paul Ritzenthaler

  • 1Université de Toulouse, UPS, Laboratoire de Microbiologie et de Génétique Moléculaires, F-31000 Toulouse, France.

Journal of Bacteriology
|December 2, 2009
PubMed

Insights

Bacteriophage mv4 uses a recombination directionality factor (RDF), (mv4)Xis, to control prophage excision. This protein is essential for DNA recombination between attR and attL sites but does not inhibit integration.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Temperate bacteriophages integrate into host genomes via site-specific recombination.
  • Prophage excision is a critical step for initiating lytic growth.
  • Recombination directionality factors (RDFs) regulate the directionality of phage-host DNA recombination.

Purpose of the Study:

  • To identify and functionally characterize the RDF involved in the site-specific excision of the bacteriophage mv4 prophage.
  • To elucidate the role of the identified RDF in the recombination process.

Main Methods:

  • Gene identification and characterization of the mv4 RDF, (mv4)Xis.
  • Electrophoretic mobility shift assays (EMSAs) to study DNA binding.
  • In vitro and in vivo recombination assays using plasmids in Escherichia coli and Lactobacillus plantarum.

Main Results:

  • The mv4 RDF, (mv4)Xis, is a 56-amino acid basic protein encoded by the early lytic operon.
  • (mv4)Xis specifically binds to attP and attR sites, inducing DNA bending.
  • (mv4)Xis is essential for attR-attL recombination but does not inhibit attP-attB integration.

Conclusions:

  • The identified (mv4)Xis protein functions as a critical recombination directionality factor for mv4 prophage excision.
  • (mv4)Xis exhibits distinct roles in regulating recombination directionality, facilitating excision while not impeding integration.
  • This study provides insights into the molecular mechanisms governing bacteriophage DNA recombination and lysogeny.

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