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The minor capsid protein gp7 of bacteriophage SPP1 is required for efficient infection of Bacillus subtilis

Inês Vinga1, Anja Dröge, Asita C Stiege

  • 1Unité de Virologie Moléculaire et Structurale, CNRS UMR 2472, INRA UMR1157 and IFR 115, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France.

Molecular Microbiology
|August 11, 2006
PubMed

Insights

The minor capsid protein gp7 in Bacillus subtilis bacteriophage SPP1 is crucial for infectivity. Deleting gp7 impairs DNA ejection, leading to reduced viral genome delivery and lower burst sizes.

Area of Science:

  • Microbiology
  • Virology
  • Molecular Biology

Background:

  • The function of the minor capsid protein gp7 in Bacillus subtilis bacteriophage SPP1 was previously unknown.
  • gp7 homologs are present in many phages, suggesting a conserved role.

Purpose of the Study:

  • To investigate the function of gp7 in SPP1 phage infection.
  • To determine the role of gp7 in viral DNA ejection and host cell entry.

Main Methods:

  • Generated a gene 7 deletion mutant (SPP1del7) of SPP1 phage.
  • Assessed viral particle assembly, morphology, and composition.
  • Performed infection assays to measure membrane depolarization and DNA ejection efficiency.
  • Conducted in vitro DNA ejection experiments.

Main Results:

  • SPP1del7 phages exhibited normal particle assembly but reduced infectivity (only 25% infectious).
  • SPP1del7 infections showed defects in host membrane depolarization and viral genome traffic.
  • Mutant phages displayed increased abortive DNA release into the medium.
  • In vitro, gp7 anchors ejected DNA to the phage particle, controlling DNA exit rate.

Conclusions:

  • gp7 is essential for efficient SPP1 phage infectivity and proper viral genome delivery.
  • gp7 regulates the rate of DNA release from the phage particle.
  • This function of gp7 is critical for routing the phage genome into the host cytoplasm.

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