Structural and Molecular Basis for Coordination in a Viral DNA Packaging Motor

Area of Science:

• Molecular Biology
• Structural Biology
• Virology

Background:

• Ring NTPases are essential molecular motors for biological processes.
• Double-stranded DNA (dsDNA) viruses utilize ring ATPases to package their genomes into viral capsids.

Purpose of the Study:

• To elucidate the structure and mechanism of the dsDNA packaging motor in bacteriophage phi29.
• To understand how ATP hydrolysis is coordinated for efficient DNA translocation.

Main Methods:

• X-ray crystallography
• Cryo-electron microscopy (cryoEM)
• Biochemical analyses

Main Results:

• Determined the pseudo-atomic structure of the pentameric ATPase ring.
• Identified ATP binding sites and two key DNA contact points, including a DNA translocating loop.
• Revealed the role of a trans-acting arginine finger in coordinating hydrolysis and coupling to the DNA translocating loop.

Conclusions:

• The structure and functional analyses provide insights into the mechanism of dsDNA translocation by viral motors.
• Visualizing the motor in action highlights the interplay between motor components and the DNA substrate.