Structural basis of Acinetobacter type IV pili targeting by an RNA virus

Area of Science:

• Microbiology
• Structural Biology
• Virology

Background:

• Acinetobacter species are significant human pathogens, particularly in immunocompromised individuals.
• Type IV pili are key virulence factors in Acinetobacter, contributing to antibiotic resistance.
• Bacterial viruses (bacteriophages) can target bacterial pili.

Purpose of the Study:

• To investigate the structural basis of the interaction between Acinetobacter phage AP205 and type IV pili.
• To characterize the structural adaptations of the phage and pili during binding.
• To engineer a novel protein-based tool for targeting type IV pili.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was used to determine high-resolution structures.
• Structural analysis of the phage virion, native type IV pili, and the pili-phage complex.
• Protein engineering to develop a phage-derived scaffold.

Main Results:

• The structure of Acinetobacter phage AP205 bound to type IV pili was solved.
• Distinct post-translational modifications of native Acinetobacter type IV pili were identified.
• The phage's maturation proteins were observed to adapt to pilin modifications for binding.
• A 20-kilodalton protein scaffold derived from AP205 was successfully developed.

Conclusions:

• The study reveals the molecular mechanism of Acinetobacter phage AP205 binding to type IV pili.
• The identified pilin modifications and phage adaptations provide insights into host-pathogen interactions.
• The engineered AP205-derived protein scaffold shows promise as a research and diagnostic tool targeting bacterial type IV pili.