Sodium fusidate prevents protein aggregation of silk fibroin and offers new perspectives for human lens material disaggregation

Silk fibroin (SF) is a non-pathological amyloidogenic protein prone, in solution, to the formation of amyloid-like aggregated species, displaying similarities in fibrillation kinetics with pathological amyloids, as widely reported in the literature. We show here, on the basis of different biophysical approaches (turbidity, Congo Red assays, CD, DLS and fluorescence), that fusidic acid (FA), a well-known antibiotic, acts on SF as an anti-aggregating agent in a dose-dependent manner, being also able to revert SF aggregation. FA binds to SF inducing changes in the environment of SF aromatic residues. We further provide the proof of principle that FA, already approved as drug on humans and used in ophthalmic preparations, displays its anti-aggregation properties also on lens material derived from cataract surgery and is capable of reducing aggregation. Thus it is suggested that FA can be foreseen as a therapeutic treatment for cataract and other protein aggregation disorders.