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Characterization of the integrase gene and attachment site for the Myxococcus xanthus bacteriophage Mx9

Bryan Julien1

  • 1Kosan Biosciences, Inc., Hayward, California 94545, USA. julien@kosan.com

Journal of Bacteriology
|October 18, 2003
PubMed

Insights

Bacteriophage Mx9 integrates into Myxococcus xanthus DNA via site-specific recombination. This integration, mediated by the Int protein, can lead to DNA deletion and alters the phage attachment site within the int gene.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Myxococcus xanthus is a bacterium known to be infected by temperate phages.
  • Temperate phages can integrate their genetic material into the host chromosome, a process called lysogeny.
  • Site-specific recombination is a key mechanism for phage integration into bacterial genomes.

Purpose of the Study:

  • To investigate the mechanism of integration of bacteriophage Mx9 into the Myxococcus xanthus chromosome.
  • To identify the specific integration sites and the proteins involved in the process.
  • To analyze the consequences of Mx9 integration on the bacterial genome and gene expression.

Main Methods:

  • Site-specific recombination analysis.
  • DNA integration site mapping (attB1 and attB2).
  • Gene expression studies using promoter-lacZ fusions.

Main Results:

  • Bacteriophage Mx9 integrates into M. xanthus at attB1 or attB2 sites via site-specific recombination.
  • Integration at attB1 results in a DNA deletion between the attB sites.
  • The phage attachment site (attP) is located within the int gene, and its 3' end is altered upon integration.
  • Reporter gene fusions showed higher transcription levels when integrated at Mx9 attB sites compared to Mx8 attB sites.

Conclusions:

  • The Int protein of Mx9 mediates site-specific integration into M. xanthus.
  • Mx9 integration involves distinct attB sites, one of which is within a tRNA gene.
  • Integration can lead to genomic alterations and affects the expression of nearby bacterial promoters.

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