The synergistic chaperoning operation in a Bi-chaperone system consisting of alpha-crystallin and beta-casein: Bovine pancreatic insulin as the target protein

While chaperone activity of alpha-crystallin (α-Crs) is important in maintaining lens transparency that of beta-casein (β-CN) is vital to prevent the development of corpora amylacea (accumulation of amyloid deposits in mammary glands). These two chaperone proteins are amphiphilic, each contains distinct polar and non-polar regions in the structure. While polar domain of α-Crs is highly electropositive, the counterpart domain in β-CN is strongly electronegative. In this study a Bi-chaperone system consisting of α-Crs and β-CN with different molar ratios were used to prevent the chemical-induced insulin aggregation spectroscopically. As shown, α-Crs and β-CN in the Bi-chaperone system exhibit synergistic chaperoning operation which strongly depends to the specific ratio of the chaperone components. The results of both fluorescence study and native gel electrophoresis confirmed the non-covalent interactions between α-Crs and β-CN. Consequently the synergistic activity can be explained with the possible electrostatic interactions between their polar/charged domains which bring them in close proximity, allowing their synergistic chaperoning operation in the Bi-chaperone system.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We used alpha-crystallin and beta-casein either individually or together to prevent the chemical induced insulin aggregation. ► The two chaperone components in the Bi-chaperone system exhibit synergistic activity, depending strongly to their specific ratio. ► The non-covalent interaction between these chaperones was confirmed by native gel electrophoresis. ► Consequently the synergistic activity can be explained with the possible electrostatic interactions between their polar/charged domains. ► The result may suggest a new example of highly efficient chaperone system.