Recombinant Silk Protein and Pigments

Replacing synthetic pigments with natural ones is a growing global trend affecting a large number of fields, such as the textile, hair, and food dyeing industries. Many synthetic dyes are toxic for the environment and humans, and they can accumulate in the environment and spoil bodies of water. In fact, the textile dyeing industry is the second largest polluter of bodies of water in the world.

Our idea for Aalto-Helsinki iGEM 2018 is to use a microbial host to produce environmentally friendly dyes together with dragline spider silk proteins. Dragline silk has exceptional strength and elasticity, but since producing recombinant silk fibers is extremely challenging at the moment, we have decided to focus on silk proteins. Silk proteins have interesting properties that could be useful in coating materials, such as textiles or hair.

The combination of silk proteins and coloured pigments can be used to make prints on textiles, using natural and environmentally friendly materials. As a hair product, silk proteins attach onto and into the keratin of the hair, providing improved strength, durability, and smoothness. Together with pigment proteins found in corals, we hope to be able to both improve hair quality, as well as give it a beautiful colour.

One of the pigments we will use is the chromoprotein Monomeric Red (mRED) from the coral species Discosoma striata, the sequence of which was obtained from the BioBrick BBa_E1010. However, we are also interested in using additional chromoproteins to produce a wider range of colors. We will construct various fusion proteins with the chromoproteins and components of spider silk proteins: repeats from the major ampullate spidroin 3 of Araneus diadematus (European garden spider) and the terminal linkers of the major ampullate spidroin 1 of Euprosthenops australis. The proteins will be produced in the E. coli strain BL21(DE3) which allows high-level expression with the T7 promoter and is ideal for recombinant proteins.

Most of our fusion proteins will contain a keratin-binding domain (KBD) from desmoplakin or a cellulose-binding domain (CBD) from the BioBrick BBa_K2342002 to facilitate binding to hair or cellulose-rich textiles such as cotton.