Work

Host-Associated Binding Patterns in Predicted Structural Models of Circovirus Capsid–Importin Complexes

Year: 2026

Type: article

Abstract: The nuclear entry of the capsid protein is a critical step in the life cycle of circoviruses, but whether capsid proteins from different circoviruses differ in their importin interactions remained unclear. Here, we modeled 298 unique circovirus capsid protein–importin pairs using AlphaFold 3. After conformational clustering and ZDOCK concordance filtering, 603 representative interfaces were retained for analysis. We extracted Δ iG values, interface features, and nuclear localization signal (NLS)-specific interface properties by PDBePISA and analyzed them with statistical tests. Capsid protein (Cap)–importin-9 (IPO9) complexes showed the lowest mean Δ iG among all tested circoviruses, identifying IPO9 as a candidate broadly interacting importin among the viruses examined. Across all host classes, Cap–importin β complexes showed a lower mean Δ iG than Cap–importin α or Cap–transportin complexes. Predicted Δ iG patterns differed across host classes, with distinct profiles for avian, mammalian, and fish circoviruses. Predicted Δ iG patterns and NLS interface features, including basic residue ratio, interface occupancy, and net charge, differed across avian, mammalian, and fish circoviruses. Together, these results provide a set of testable predictions regarding circovirus Cap–importin interfaces and highlight the predicted NLS interface as a region for further investigation.

Source: Computational and Structural Biotechnology Journal

DOI: 10.34133/csbj.0253