Engineering self-cleavage fusion system for the Production of Chimera Spider Silk Proteins

Abstract

Abstract The spider silk protein (spidroin), which has powerful mechanical properties, has been extensively studied and shown potential application in various fields. The predatory nature of spiders makes native spidroin challenging to obtain, while heterologous expression of spidroin was hindered by the gene sequence features such as highly repetitive regions and high GC content. The low yield of spidroin subsequently affects its further application. In this study, we constructed a convenient expression system by employing a fusion tag in combination with a self-cleavage intronic peptide (intein) for three kinds of chimeric spidroins with different numbers of repetitive units, and soluble expression of the three kinds of spidroins after optimizing expression conditions was achieved with yields of 266 mg/L (NT2RepCT), 135 mg/L (NT4RepCT), and 125 mg/L (NT6RepCT), respectively. Three kinds of chimeric spidroins displayed increased β-sheet content with increased repetitive units during the transition from the solution to the dry state. Their capacity to form filamentous fibrils increased with the number of repetitive numbers. This study provides a solution for spidroin soluble expression and lays a foundation for its future application.