IncI2 plasmids specify sensitivity to filamentous bacteriophage IKe

Area of Science:

• Microbiology
• Virology
• Molecular Biology

Background:

• IncI2 plasmids are a group of bacterial plasmids known to determine specific pilus structures.
• Filamentous bacteriophages are viruses that infect bacteria, often utilizing surface structures like pili for adsorption.

Purpose of the Study:

• To investigate the interaction between IncI2 plasmids and filamentous bacteriophages.
• To determine which bacteriophages can lyse bacteria carrying IncI2 plasmids and identify their adsorption targets.

Main Methods:

• Bacterial strains harboring derepressed IncI2 plasmids (TP114drp-l or R721pilc) were subjected to lysis by filamentous bacteriophages (IKe, I2-2, X).
• Serological relationships between phages were assessed.
• Phage adsorption to specific pilus structures (thick vs. thin pili) was examined.

Main Results:

• Phages IKe, I2-2, and X were capable of lysing bacteria carrying IncI2 plasmids.
• Phage I2-2 showed serological similarity to phage IKe, while phage X did not.
• Phage IKe preferentially adsorbed to the tips of thick pili, which are determined by the IncI2 plasmids, and not to the thin I2 pili.

Conclusions:

• The study demonstrates that specific filamentous bacteriophages can infect and lyse bacteria harboring IncI2 plasmids.
• Phage IKe utilizes a distinct mechanism by targeting plasmid-determined thick pili for adsorption, differentiating it from other phages and pilus types.