Mind the gap: how some viruses infect their hosts

Area of Science:

• Structural biology
• Microbiology
• Virology

Background:

• Cryo-electron microscopy (Cryo-EM) and cryo-electron tomography (Cryo-ET) are powerful techniques for visualizing biological structures at high resolution.
• Podoviridae are a family of double-stranded DNA (dsDNA) bacteriophages characterized by short, non-contractile tails.
• These phages possess the ability to translocate their genetic material into the cytoplasm of their bacterial hosts.

Purpose of the Study:

• To investigate the structural dynamics of podoviridae phage infection using advanced cryo-EM techniques.
• To elucidate the molecular mechanisms underlying DNA translocation from the phage P-SSP7 into its host, Pseudomonas marinus.
• To provide novel structural insights into a critical step of viral infection.

Main Methods:

• Application of cryo-electron microscopy (Cryo-EM) for high-resolution imaging of phage particles.
• Utilization of cryo-electron tomography (Cryo-ET) to capture three-dimensional structural changes during the infection process.
• Infection of Pseudomonas marinus with the podoviridae phage P-SSP7 as a model system.

Main Results:

• Detailed structural analysis of the P-SSP7 phage before, during, and after DNA injection.
• Identification of specific structural rearrangements in the phage tail and capsid associated with DNA translocation.
• Visualization of the interface between the phage and the host cell membrane during infection.

Conclusions:

• The study provides unprecedented molecular detail on the DNA injection mechanism of podoviridae phages.
• Cryo-EM and Cryo-ET are essential tools for dissecting complex viral infection processes.
• Understanding phage-host interactions at a structural level can inform future antiviral strategies.