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Area of Science:

  • Molecular Biology
  • Biophysics
  • Virology

Background:

  • Bacteriophages infect bacteria by injecting double-stranded DNA into the host cytosol.
  • The process and timing of DNA ejection from the viral capsid remain incompletely understood.
  • DNA packaging within the capsid influences ejection dynamics.

Purpose of the Study:

  • To investigate the factors controlling the timescales of DNA ejection from bacteriophages.
  • To elucidate the role of DNA topology and organization within the capsid on ejection properties.
  • To understand the relationship between DNA knotting and ejection efficiency.

Main Methods:

  • Stochastic simulations were employed to model DNA ejection dynamics.
  • Analysis focused on the influence of DNA spatial organization (spools vs. entangled states).
  • Investigated the impact of DNA knot types and topological complexity on ejection.

Main Results:

  • Spatially ordered DNA spools exhibit significantly lower effective friction compared to disordered, entangled states.
  • Local DNA strand alignment is crucial for forming ordered spools, impacting friction.
  • DNA knot type influences ejection, with complex knots slowing or arresting the process; torus knots unravel stepwise.

Conclusions:

  • DNA topology and internal organization are critical determinants of bacteriophage DNA ejection timescales.
  • Topological friction, dependent on knot type, modulates ejection efficiency.
  • Simulated DNA knotting patterns during ejection correlate with experimental observations from viral DNA.