Single DNA molecule jamming and history-dependent dynamics during motor-driven viral packaging

Area of Science:

• Biophysics
• Molecular Virology
• Soft Matter Physics

Background:

• Viruses use molecular motors to pack DNA into prohead shells.
• DNA packaging reaches near-crystalline densities within nanoscale viral capsids.
• Unexpected stalling is observed under conditions promoting attractive DNA-DNA interactions.

Purpose of the Study:

• Investigate the mechanism behind DNA packaging stalling in viral proheads.
• Determine if DNA undergoes a jamming transition during viral DNA packaging.
• Extend the concept of jamming to single polymer molecules.

Main Methods:

• Utilized experiments involving changes in conditions during DNA packaging.
• Switched DNA-DNA interactions between repulsive and attractive states.
• Analyzed history-dependent dynamics and stalling phenomena.

Main Results:

• DNA packaging frequently stalls when attractive DNA-DNA interactions are induced.
• Stalling is linked to a nonequilibrium jamming transition of the DNA.
• Observed abrupt deceleration before stalling, indicating conformational changes and increased resistance.
• Single DNA molecules jam over a broader density range than colloidal particles.

Conclusions:

• The jamming transition concept can be extended to single polymer molecules like DNA.
• Nanoscale system size influences jamming behavior, differing from macroscopic systems.
• History-dependent dynamics are crucial in understanding DNA packaging stalling.