FhuA-mediated phage genome transfer into liposomes: a cryo-electron tomography study

Area of Science:

• Microbiology
• Structural Biology
• Molecular Biology

Background:

• Bacteriophage genome transfer into host cells is poorly understood.
• Phage DNA is released from the capsid and crosses the bacterial cell envelope.
• Phage T5 interaction with E. coli receptor FhuA triggers DNA release.

Purpose of the Study:

• To elucidate the mechanism of phage T5 DNA transfer into Escherichia coli.
• To visualize phage-bacterial interactions at a molecular level.

Main Methods:

• Cryo-electron tomography was used to analyze T5 phages bound to FhuA-containing proteoliposomes.
• Three-dimensional reconstructions provided high-resolution visualization of the interaction and DNA transfer process.

Main Results:

• The T5 phage tail tip penetrates the bacterial outer membrane (lipid bilayer).
• The tail tip undergoes a conformational change, shrinking in length and increasing in diameter during DNA transfer.
• 121,000 base pairs of double-stranded DNA were successfully transferred into proteoliposomes.

Conclusions:

• The outer membrane receptor FhuA serves as a docking site for the phage.
• The phage tail tip functions as an injection needle, creating a passage for DNA translocation.
• A mechanistic model for viral genome transfer across the bacterial membrane is proposed.