Transgenic silkworms (Bombyx mori) produce recombinant spider dragline silk in cocoons

Abstract

Spider dragline silk is a unique fibrous protein with a combination of tensile strength and elasticity, but the isolation of large amounts of silk from spiders is not feasible. In this study, we generated germline-transgenic silkworms (Bombyx mori) that spun cocoons containing recombinant spider silk. A piggyBac-based transformation vector was constructed that carried spider dragline silk (MaSp1) cDNA driven by the sericin 1 promoter. Silkworm eggs were injected with the vector, producing transgenic silkworms displaying DsRed fluorescence in their eyes. Genotyping analysis confirmed the integration of the MaSp1 gene into the genome of the transgenic silkworms, and silk protein analysis revealed its expression and secretion in the cocoon. Compared with wild-type silk, the recombinant silk displayed a higher tensile strength and elasticity. The results indicate the potential for producing recombinant spider silk in transgenic B. mori.

Silkworms transformed with chimeric silkworm/spider silk genes spin composite silk fibers with improved mechanical properties

“…The use of piggyBac vectors with these features has yielded transgenic silkworm lines that produced composite fibers containing a variety of different recombinant proteins, including procollagen (28), GFP (27,29), and feline IFN (30). In addition, while our work was in progress, others isolated transgenic silkworms that can produce spider silk proteins (35,36). A transgenic silkworm engineered to produce a spider silk protein was isolated using a piggyBac vector encoding a native N. clavipes major ampullate spidroin-1 silk protein under the control of a B. mori sericin (Ser1) promoter (35).…”

“…In addition, while our work was in progress, others isolated transgenic silkworms that can produce spider silk proteins (35,36). A transgenic silkworm engineered to produce a spider silk protein was isolated using a piggyBac vector encoding a native N. clavipes major ampullate spidroin-1 silk protein under the control of a B. mori sericin (Ser1) promoter (35). The spidroin sequence was fused to a downstream sequence encoding a Cterminal fhc peptide.…”

“…Thus, we engineered our vectors with the fhc promoter to express the chimeric silkworm/spider silk protein in the same place and at the same time as the native silk proteins and facilitate stable integration of the chimeric protein into newly assembled, composite silk fibers. Wen et al (35) detected minor increases in the elasticity and tensile strength of fibers in cocoons from their transgenic silkworms. However, they did not remove the sericin layer before mechanical testing, which is an essential cocoon step in commercial silk fiber production.…”

Recombinant Spider Silks—Biopolymers with Potential for Future Applications

“…This vector was then injected into silkworm embryos, and successful transgenic individuals were mated to generate G2 descendants. The MaSp1 fragment was found in the sericin layer surrounding the silk fibers of these transgenic silkworms [37].…”

Silk Fibers as Smart Materials Toward Medical Textiles

“…Spider silk was produced in a silk sericin layer using transgenic silkworm technology [33] and using Baculovirus expression systems [34]. However, the latter two attempts were unable to form fibers.…”