Recombinant DNA production of spider silk proteins

Abstract

Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce recombinant spider silks.

Figure 1

A. An adult female orb weaver spider Nephila clavipes and her web. B. Schematic overview of N. clavipes web composed of three different spider silk proteins and their structures. The coloured boxes indicate the structural motifs in silk proteins. An empty box marked ‘?’ indicates that the secondary structure of the ‘spacer’ region is unknown. Note: MaSp1 or MaSp2: major ampullate spidroin 1 or 2; MiSp1 and 2: minor ampullate spidroin1 and 2; Flag: flagelliform protein. The photo was taken by Olena and Artem Tokarev in the Florida Keys.

Figure 2

Recombinant DNA approach used to prepare silk-like proteins.

Figure 3

Gene multimerization approaches. Note: RE Site stands for a restriction enzyme site.

Figure 4

Cloning strategy used by the Lewis group to engineer long repetitive spider silk sequences (in green). A. Cloning of a silk monomer into the vector pBluescript II SK+. B. The resulting plasmid is double digested and fragments containing silk monomers are ligated again to produce longer sequences. C. The synthetic spider silk multimer is ligated into pET19b expression vector. Note: Restriction digestion sites are indicated by star. Adapted from reference (Teule et al., 2009).

Figure 5

Expression of the chimeric silkworm/spider silk/EGFP protein in (A) cocoons, (B and C) silk glands and (D) silk fibres from spider 6-GFP silkworms. Reproduced with permission from (Teulé et al., 2012b).