Simvastatin and Lovastatin inhibit Bacillus subtilis biofilm formation by interfering with the aggregation and amyloid formation of the TasA(28-261) –TapA(33-253) complex.

Abstract Statins have been reported for diverse pleiotropic activities, including antimicrobial and antibiofilm. However, due to the limited understanding of their mode of action, none of the statins have gained approval for antimicrobial or antibiofilm applications. In a recent drug-repurposing study, we observed that two statins (i.e., Simvastatin and Lovastatin) interact stably with TasA₍₂₈₋₂₆₁₎, the principal extracellular matrix protein of Bacillus subtilis, leading to the inhibition of biofilm formation. Nevertheless, the precise mechanism underlying the biofilm inhibition remained elusive. In the present study, we examined the impact of these statins on the physiological activity of TasA₍₂₈₋₂₆₁, specifically its interaction with TapA₍₃₃₋₂₅₃₎ and aggregation into the amyloid-like structure using purified recombinant TasA₍₂₈₋₂₆₁₎ and TapA₍₃₃₋₂₅₃₎ in amyloid detection specific in vitro assays (i.e., CR binding & ThT staining assays). Results revealed that both statins interfered with amyloid formation by TasA₍₂₈₋₂₆₁₎-TapA₍₃₃₋₂₅₃₎ complex, while neither statin inhibited amyloid formation by lysozyme, a model amyloid-forming protein. Moreover, neither statin significantly altered the expressions of terminal regulatory genes (viz., sinR, sinI) and effector genes (viz., tasA, tapA, and bslA) involved in biofilm formation by B. subtilis. These findings divulge that Simvastatin and Lovastatin inhibit biofilm formation by B. subtilis by interfering with the aggregation and amyloid formation by TasA₍₂₈₋₂₆₁₎–TapA₍₃₃₋₂₅₃₎. These results represent one of the first experimental evidences for the underlying mechanism of antibiofilm activity of statins and offer valuable directions for future research to harness statins as antibiofilm therapeutics.