Molecular docking of Pyocyanin from Pseudomonas aeruginosa with NADPH oxidase and Toll-like receptor 4 : Exploring the Link Between Oral Microbiome and Oral Cancer Pathogenesis

Oral cancer is among the leading cancers in India, with its progression influenced not only by genetic and environmental factors but also by dysbiosis in the oral microbiome. Pseudomonas aeruginosa, an opportunistic Gram-negative bacterium, has been implicated in oral carcinogenesis through the action of its virulence factor, pyocyanin--a redox-active phenazine that induces reactive oxygen species (ROS), promoting oxidative stress, immune dysregulation, and inflammation. Despite evidence linking pyocyanin to ROS-related pathways, its molecular interaction with key host proteins like NADPH oxidase and Toll-like receptor 4 (TLR4) remains unexplored. The present study aims to investigate the molecular interactions of pyocyanin with NADPH oxidase and TLR4 through molecular docking, aiming to elucidate its role in oxidative and inflammatory mechanisms associated with oral cancer pathogenesis. The structures of pyocyanin and the NADPH oxidase (NOX2) and TLR4 target proteins were retrieved from PubChem and RCSB PDB, respectively. CASTp was used to identify potential binding pockets. Molecular docking was performed using the HADDOCK server. The docked complexes were analyzed based on HADDOCK scores, binding energies, RMSD, and buried surface area. Interaction profiles were visualized using BIOVIA Discovery Studio. Among the docking clusters, Cluster 6 for the NOX2-pyocyanin complex showed a favorable HADDOCK score (84.4 {+/-} 2.9), low RMSD (0.2 {+/-} 0.0), and substantial buried surface area (456.1 {+/-} 13.2 [A]2). For the TLR4-pyocyanin complex, Cluster 1 exhibited the most favorable interaction profile with a HADDOCK score of 25.0 {+/-} 5.5 and a Z-score of -2.3. Binding site prediction and hydropathy analysis supported the structural feasibility of pyocyanin interaction with both targets. This study provides structural insights into the potential interaction of pyocyanin with NADPH oxidase and TLR4, supporting its role in modulating oxidative stress and inflammatory signaling pathways. These findings enhance our understanding of oral microbiome-host interactions and their contribution to oral cancer pathogenesis.