Vol. 9, Special Issue 12, Part B (2025)

Tomato Leaf Curl Virus (ToLCV) employs the multifunctional AC2 protein to manipulate host defense pathways, yet its potential interaction with the SUMOylation system remains unexplored. In this study, we investigated the structural basis and dynamic stability of the tomato SUMO1-AC2 complex using homology modeling, molecular docking, and long-timescale molecular dynamics simulations. Docking indicated favorable binding between SUMO1 and AC2, and MD simulations demonstrated that the complex remains stable, compact, and well-structured throughout 120 ns. RMSD, radius of gyration, surface area, and hydrogen-bond analyses confirmed the absence of large-scale unfolding or dissociation, while RMSF revealed flexibility mainly in loop regions of AC2. Secondary-structure profiles indicated retention of native folding patterns for both proteins. These findings suggest that AC2 can stably associate with SUMO1, potentially enabling ToLCV to interfere with SUMO-dependent immune regulation in tomato. The SUMO1-AC2 interface represents a promising target for engineering resistance against begomoviruses.