Host Systems for the Production of Recombinant Spider Silk

Abstract

Spider silk is renowned for its impressive mechanical properties. It is one of the strongest known biomaterials, possessing mechanical properties that outmatch both steel and Kevlar. However, the farming of spiders for their silk is unfeasible. Consequently, production of recombinant spider silk proteins (spidroins) in more amenable hosts is an exciting field of research. For large-scale production to be viable, a heterologous silk production system that is both highly efficient and cost effective is essential. Genes encoding recombinant spidroin have been expressed in bacterial, yeast, insect, and mammalian cells, in addition to many other platforms. This review discusses the recent advances in exploiting an increasingly diverse range of host platforms in the heterologous production of recombinant spidroins. Highlights Recombinant spidroins of comparable size and mechanical function to native silk proteins have been successfully produced by engineered E. coli. Recombinant spidroins have been expressed in transgenic plants, rice, and alfalfa. These expression platforms can potentially offer increased industrialscale economic viability over alternative host systems.

Recent developments in sustainably sourced protein-based biomaterials

“…Composite silk spidroin spheres, therefore, offer a cancer drug delivery system which is targeted, controlled and biodegradable [ 113 ], potentially enhancing patient outcomes and reducing overall medical costs. Bioengineered silk is more sustainable than traditional silk harvesting, with recombinant systems being designed in prokaryotic and eukaryotic models including Escherichia coli , rice, tobacco, and kidney cells [ 114 ]. If green production and processing of silk fibroin and spidroin become commonplace, the use of silk biomaterials for drug delivery could be utilised for consumer products.…”

Engineered proteins as multifunctional materials

“…As native sourcing from spiders is not feasible, significant effort has been invested in porting spider silk genes into diverse hosts spanning bacterial, yeast, arthropod, mammalian, and plant systems (Figure 2). 8 Of these hosts, the silkworm, Bombyx mori, is a promising vehicle for silk fiber production as it naturally spins aqueous silk protein into solid fiber. Genome editing tools such as clustered regularly interspaced palindromic repeats (CRISPR/Cas9), transposon vectors, and transcription activator-like effector nucleases (TALEN) have been utilized to deliver the spidroin gene sequence to silkworm embryos creating miniature recombinant silk extruding bioreactors.…”

Native Spider Silk-Based Antimicrobial Hydrogels for Biomedical Applications

“…Nevertheless, the involvement of natural spider silk in the material industry is yet to be developed due to the potential complications and disadvantages of artificial silk synthesis [ 53 ]. Mainly, recombinant spider silk synthesis requires extended time and different host organisms to facilitate its production [ 54 ]. Different types of recombinant hosts have been investigated recently, and it shows diverse complications of the synthesis process in different hosts [ 55 ].…”

“…Furthermore, the genetic rearrangement and the repeated sequence insertions may produce altered or unknown amino acid sequences [ 57 ]. The main obstacle, however, is assumed to be the extraction and purification of the spider silk proteins from the host [ 54 ]. Different studies confirm that the cytosolic aggregation of silk proteins within the host cytosol may affect the purification and lowering of the protein yield [ 54 ].…”

“…The main obstacle, however, is assumed to be the extraction and purification of the spider silk proteins from the host [ 54 ]. Different studies confirm that the cytosolic aggregation of silk proteins within the host cytosol may affect the purification and lowering of the protein yield [ 54 ]. Based on experience in SCAMT Institute’s insectarium, it was found that one adult spider (based on the example of Linothele Fallax spider) can secrete up to 10 mg of silk per day according to different phases of their life cycle, and these spiders can live up to 25 years [ 58 , 59 ].…”