Production of recombinant coiled coil silk proteins for materials synthesis

Abstract

Rational design of fundamentally new advanced materials would be facilitated by availability of polymers with controlled monomer sequence. Recombinant proteins offer polymers with controlled monomer sequence but are underrepresented in material science, in part because suitable proteins cannot be produced at commercial levels in recombinant systems. The silk proteins of honeybees fulfil the requirements for rational materials design and can be produced at commercially viable levels. In this study we compare recombinant expression of these silks in bacteria, yeast and insect cells to identify the most suitable method of silk protein production. Yeast and insect cell lines are unlikely to be suitable expression platforms for these silks as the recombinant proteins were degraded, expression levels were low or absent, and host cell protein levels were high. We confirm that expression into E. coli inclusion bodies using defined media offers high level expression and to date is the best expression system for these proteins.