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Genome analysis of an inducible prophage and prophage remnants integrated in the Streptococcus pyogenes strain SF370

Carlos Canchaya1, Frank Desiere, W Michael McShan

  • 1Nestlé Research Center, Nestec Ltd. Vers-chez-les-Blanc, CH Lausanne 26, Switzerland.

Virology
|November 21, 2002
PubMed

Insights

This study characterizes Streptococcus pyogenes prophage SF370.1, revealing its genetic makeup and relationship to other phages. It highlights phage-host interactions, suggesting cooperation and an evolutionary arms race.

Area of Science:

  • Microbiology
  • Virology
  • Genomics

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • Bacteriophages (phages) can integrate into bacterial genomes as prophages.
  • Understanding prophage genomes is crucial for deciphering phage-host interactions and bacterial evolution.

Purpose of the Study:

  • To characterize the mitomycin C inducible prophage SF370.1 from a highly pathogenic Streptococcus pyogenes strain.
  • To investigate the genetic organization and evolutionary relationships of SF370.1 with other known phages.
  • To identify and analyze other prophage-like elements within the S. pyogenes SF370 genome.

Main Methods:

  • Genome sequencing and analysis of prophage SF370.1.
  • Comparative genomics to determine relatedness to other Siphoviridae phages.
  • Bioinformatic screening of the S. pyogenes SF370 genome for additional prophage elements.
  • Analysis of integration sites and genetic context of prophages.

Main Results:

  • Prophage SF370.1 possesses a 41-kb genome with genetic organization similar to SF11-like pac-site Siphoviridae.
  • SF370.1 is most closely related to prophage NIH1.1 and shows decreasing relatedness to other bacterial and archaeal phages.
  • The study identified additional prophage remnants (e.g., SF370.4) and phage-like integrases within the S. pyogenes SF370 genome.
  • Prophage elements were found integrated into coding sequences, including DNA repair genes, and encoded virulence factors like pyrogenic exotoxin C.

Conclusions:

  • Prophage SF370.1 encodes lysogenic conversion genes, including pyrogenic exotoxin C, contributing to S. pyogenes pathogenicity.
  • The integration of prophages into host genomes can lead to significant genomic alterations and influence bacterial evolution.
  • The findings support a hypothesis of ongoing cooperation and evolutionary "arms race" between phage and host genomes.

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