Hen egg Lysozyme fibrils act as amyloid nucleating agents for β-lactoglobulin and Insulin

Abstract

Understanding the mechanism of amyloid cross-seeding process has become fundamentally important to the understanding of the molecular mechanism of the pathogenesis of amyloid associated diseases. Hence, the intrinsic crosstalk potential between different amyloidogenic proteins becomes an important area of investigation that explores how the amyloid fibrils of one type of protein would induce amyloid aggregation of other protein types. Here, we have explored the cross-seeding effect of Lysozyme amyloid fibrils on two important amyloidogenic proteins: type II diabetes linked Insulin hormone and food protein β-lactoglobulin. The Lysozyme amyloid fibrils were found to effectively induce cross-seeding reactions in Insulin and β-lactoglobulin, leading to their amyloid aggregation. Experimental and computational data showed that both monomeric and fibrillar structures of Lysozyme have strong binding affinity for Insulin as well as β-lactoglobulin via stable non-covalent interactions dominated by H-bonds and hydrophobic contacts. Our data clearly demonstrate that the cross-β structure of Lysozyme can trap native structures of both Insulin and β-lactoglobulin; however, marginal higher affinity for the monomers of β-lactoglobulin had resulted in faster kinetics of the cross-seeding reactions. At monomeric level, we also observed rapid coaggregation process for heteromeric combinations of the proteins. The results signify that amyloid cross-seeding/coaggregation could be central to the pathogenesis of the growth of amyloid deposits and targeting cross-seeding may help in developing better antiamyloid strategies.