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Protein p56 from the Bacillus subtilis phage phi29 inhibits DNA-binding ability of uracil-DNA glycosylase

Gemma Serrano-Heras1, José A Ruiz-Masó, Gloria del Solar

  • 1Instituto de Biología Molecular Eladio Viñuela (CSIC), Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain.

Nucleic Acids Research
|August 19, 2007
PubMed

Insights

Bacillus subtilis phage 29 protein p56 inhibits uracil-DNA glycosylase (UDG) by mimicking DNA. This viral protein binds to UDG, blocking its DNA repair function and revealing a novel DNA mimicry mechanism.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Virology

Background:

  • Uracil-DNA glycosylase (UDG) is crucial for DNA base excision repair.
  • Protein p56 from Bacillus subtilis phage 29 is a unique viral inhibitor of UDG.
  • The mechanism of p56-mediated UDG inhibition is not fully understood.

Purpose of the Study:

  • To elucidate the mechanism by which protein p56 inhibits uracil-DNA glycosylase (UDG).
  • To characterize the structural properties of protein p56.
  • To investigate the interaction between p56 and UDG.

Main Methods:

  • Analytical ultracentrifugation to determine protein p56 oligomerization state.
  • Circular dichroism spectroscopy to analyze protein p56 secondary structure.
  • In vitro biochemical assays using Escherichia coli UDG to study enzyme inhibition.

Main Results:

  • Protein p56 forms dimers at physiological concentrations.
  • Protein p56 exhibits a high beta-strand content (~40%).
  • p56 competes with DNA for UDG binding and blocks DNA interaction, acting as a DNA mimic.

Conclusions:

  • Protein p56 is a novel inhibitor of uracil-DNA glycosylase (UDG).
  • p56 functions as a DNA mimic, interfering with UDG's DNA binding.
  • The findings suggest a new strategy for viral evasion of host DNA repair mechanisms.

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