Structural and Functional Characterization of Type IV Pilus-Associated Proteins PilV, Pil94, and Pil96 of Aeromonas hydrophila: Potential Role in Human Pathogenesis.

OBJECTIVE

Recent genomic analyses identified a distinct pilVWXY operon in hypervirulent Aeromonas hydrophila ATCC 7966, encoding PilV and two previously uncharacterized orthologs, AHA_0694 (Pil94) and AHA_0695 (Pil96), hypothesized to mediate host-pathogen interactions.

METHODS

Complete A. hydrophila genomes (n = 53) were retrieved from NCBI, and the distribution of pilV, pil94, and pil96 was assessed using STRING v11.5. Physicochemical and structural features were analyzed via ExPASy-ProtParam, homology modeling, and validation using RAMPAGE, ProQ, and ProSA. Representative models were docked with eight human β- integrins using the HADDOCK server and evaluated by HADDOCK score, cluster size, van der Waals energy, RMSD (root-mean-square deviation), buried surface area, and Z-score.

RESULTS

Twenty-eight strains of A. hydrophila (predominantly hypervirulent) encoded all three proteins, whereas 11 non-virulent strains lacked them. Structural modelling revealed a conserved lollipop-like conformation with an extended N-terminal α-helix characteristic of Type IV pilins. Docking simulations indicated selective, high-affinity binding patterns (PilV with Integrin β3/β4/β7; Pil94 with integrin β1/β2/β3/β5; Pil96 with integrin β1/β3/β5/β7/β8), suggesting roles in multi-tissue adhesion and systemic dissemination.

CONCLUSION

The restricted occurrence of pilV, pil94, and pil96 in virulent strains and their predicted affinity for human β-integrins underscore their importance in host colonization and pathogenesis, identifying them as promising molecular targets for diagnostic or therapeutic development.