“In Silico” prediction of antibiotics biodegradation by Ganoderma lucidum GILCC 1 laccase

Abstract

Antibiotics present a pressing environmental challenge as emerging pollutants due to their persistence and role in promoting antibiotic-resistant bacteria. To model the utilization of Ganoderma lucidum GlLCC1 laccase in degrading antibiotics, a 3D homology model of GILCC1, based on Lentinus tigrinus mushroom laccase, was utilized. Five broad-spectrum WHO-designated antibiotics with molecular weights between 100 and 500 Da were selected. Molecular dynamics simulations were conducted at pH 3.0 and 7.0 to evaluate the interactions between GILCC1 and antibiotics in a TIP3P water box, with system behaviour assessed at 300 °K using an NPT assembly. ABTS (2,2ʹ-Azino-bis (3-ethylbenzthiazoline-6-sulfonic Acid)) served as the comparison molecule. The binding free energy indicated a strong affinity between 3D GILCC1 and various ligands. At pH 3.0, GILCC1 exhibited significant Gibbs free energy (ΔG), indicating a high affinity for Levofloxacin (LVX; −8.2 kcal mol−1), Sulfisoxazole (SFX; −7.8 kcal mol−1), Cefuroxime (CXM; −7.5 kcal mol−1), Cephradine (CFD; −7. 5 kcal mol−1), ABTS (−7.6 kcal mol−1), and Tetracycline (TE; −7.5 kcal mol−1), attributed to pocket topology and interactions such as hydrogen bonds and van der Waals forces. Electron transfer in GILCC1 involved a chain of residues, including His395 and Phe239. Although the affinity decreased at pH 7.0, the potential of GILCC1 to degrade antibiotics remained plausible. This study accurately predicted the behaviour of the laccase-antibiotic system, providing atomic-level insights into molecular interactions and emphasizing the importance of experimental assays and assessments of antibiotic degradation in wastewater, considering various chemical compounds. The use of ABTS as a mediator was suggested to enhance molecule affinity.Graphical abstract