Dispersin B And Its Variants In Anti-Streptococcus Mutans Biofilm

Screen, investigate and modify the enzyme with anti-Streptococcus mutans biofilm activity. We firstly summarized and evaluated the antibiofilm activities of seven enzymes, and choose one for following experiments. The effects of the selected enzyme on its substrate and biofilm were confirmed by enzymatic reactions, immunofluorescence electron microscopy (IEM), SEM, and TEM. The active pocket and key binding residues of enzyme with its substrate were predicted via molecular docking and molecular dynamics simulations. We further designed the enzyme variants, synthesized and investigated their antibiofilm efficacy. Among the seven enzymes (dispersin B, mutanase, dextranase, collagenase, dispase II, cellulase and lysozyme), only Dispersin B (0.25 mg/mL) exhibited significant biofilm inhibition, and we firstly confirmed PNAG (the substrate of dispersin B) presence in S. mutans biofilms by IEM, showing colocalization with EPS, further studies of SEM and TEM verified the decreased extracellular matrix in biofilm by using dispersin B, and quantified degradation kinetics proved the degradation of PNAG. Molecular dynamics revealed PNAG binded to dispersin B’s active pocket via hydrogen bonds with residues 27, 332, and 333, which were set as the preserved conditions to computationally engineered dispersin B variants. Two modified dispersin B variants were synthersized and showed significantly increased antibiofilm effects, and enhanced degradation of PNAG, which was further proved by molecular docking of enhanced PNAG-binding affinity. Dispersin B inhibits S. mutans biofilm formation by degrading PNAG, and our computational modified dispersin B variants showed enhanced anti-biofilm efficacy, suggesting their potential use caries prevention.