Discovering Potential OryR Inhibitors via Structural Modeling and Virtual Screening: A Computational Strategy to Control Xanthomonas oryzae pv. oryzae Virulence

Bacterial blight in rice, caused by Xanthomonas oryzae pv. oryzae (Xoo), poses a serious threat to global rice production. The ability of Xoo to form biofilms is a key factor for its virulence. The OryR protein is a LuxR-type quorum-sensing regulator essential for biofilm formation and Xoo pathogenicity. However, the three-dimensional structure of OryR remains poorly understood. This study integrates homology modeling, molecular dynamics (MD) simulations, and virtual screening to elucidate the structure of OryR and identify potential inhibitors that target its ligand-binding domain. MD simulations confirmed the structural stability of OryR, and comparative analysis with experimentally determined structures of ligand- or inhibitor-bound homologs revealed a binding site in OryR with a distinct hourglass-like shape for long-range contacts. Virtual screening of over 200,000 compounds from four chemical libraries identified several promising inhibitor candidates, with the top compounds showing strong binding energies in both molecular mechanics-generalized Born surface area (−68.3 kcal/mol) and molecular mechanics Poisson–Boltzmann surface area (−19.3 kcal/mol) calculations. Overall, this study provides insights into the OryR structure and highlights potential inhibitors that can be developed as novel agents to control bacterial blight. However, additional experimental validations are required to refine and optimize these leads for drug development.