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Role of DNA-DNA sliding friction and non-equilibrium dynamics in viral genome ejection and packaging

Mounir Fizari, Nicholas Keller, Paul J Jardine

    Biorxiv : the Preprint Server for Biology
    |April 17, 2023
    PubMed

    Insights

    Viral DNA ejection is governed by DNA-DNA friction and clogging. This nanoscale friction controls DNA exit speed but does not impact DNA packaging dynamics within the viral capsid.

    Area of Science:

    • Virology
    • Biophysics
    • Nanotechnology

    Background:

    • Viruses eject DNA through nanochannels, driven by internal forces from genome packing.
    • The dynamics of DNA ejection are limited by friction, but its nature remains poorly understood.

    Approach:

    • Utilized optical tweezers to measure DNA exit velocity from phage phi29 capsids.
    • Investigated DNA mobility under variable applied forces to understand friction's role.

    Key Points:

    • Observed extremely low initial exit velocity, exponentially increasing velocity, and stochastic pausing.
    • Identified DNA-DNA sliding friction as the primary controller of initial exit velocity.
    • Found evidence of dynamic heterogeneity and 'clogging' phenomena influencing DNA ejection kinetics.

    Conclusions:

    • DNA-DNA friction and clogging phenomena are key regulators of viral DNA exit dynamics.
    • The identified friction mechanisms primarily influence DNA ejection, not DNA packaging.
    • Experimental findings support theoretical predictions for viral DNA ejection processes.

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