What it is
Pilus-dependent phages that infect Pseudomonas aeruginosa attach to its type IV pilus, whose major subunit, PilA, shows extensive sequence and chemical diversity while remaining essential for their attachment. Combining comparative genomics with structural and functional analyses, the authors found that pilin variation is concentrated at solvent-exposed regions, altering the filament's surface chemistry while preserving the interfaces needed for pilus assembly, and that phages recognized divergent pilins more effectively than polyclonal antisera. Phages differed markedly in how much receptor variation they tolerated, and comparisons of AlphaFold3 models revealed two structurally distinct classes of tail fiber associated with those differences.
Why it matters
Viruses must recognize host receptors to infect, yet receptors can evolve rapidly, which poses a fundamental challenge to viral persistence. The study suggests that modular diversification of tail fibers is a structural route by which phages accommodate receptor evolution: phages whose tail fibers had structurally and sequence-conserved C-terminal domains were more sensitive to receptor changes, while those with structurally conserved but sequence-diverse domains infected strains expressing highly divergent pilins.
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Filed underBacteriophages and microbial interactions, Monoclonal and Polyclonal Antibodies Research, Bacterial Genetics and Biotechnology