Researchers report the stable expression of high yields of spider silk in transgenic silkworms. The high strength and elasticity of spider silk render it a desirable raw material for construction, defense, and biomedical applications. However, spiders are difficult to rear due to their territorial and cannibalistic nature. Previous efforts to engineer spider silk proteins into silkworms relied on the random insertion of spider silk genes into the silkworm genome and produced transgenic worms that spun fibers with poor yields of the spider silk protein. Using the genome editing tool TALEN, Anjiang Tan and collegues replaced FibH, the gene for the heavy chain of the major silk protein fibroin, in silkworms (Bombyx mori) with the major ampullate spidroin-1 gene, MaSp1, from the golden orb-web spider (Nephila clavipes). The authors used a cellular process termed homology-directed repair to replace silkworm FibH with a synthetic construct composed of MaSp1 and a partial FibH sequence, while allowing the silkworm's own FibH gene-regulating elements to drive the expression of the construct. Individual cocoon shells of the resulting transgenic silkworms harbored 35.2% w/w--up to 13.6 mg--of MaSp1 protein on average, and the transgenic silk fibers were less strong but more elastic and extensible than fibers from wild-type silkworms. According to the authors, the findings furnish a stable genetic expression system that could pave the way for the mass production of spider silk.
Article #18-06805: "Mass spider silk production through targeted gene replacement in Bombyx mori," by Jun Xu et al.
MEDIA CONTACT: Anjiang Tan, Shanghai Institutes for Biological Sciences, Shanghai, CHINA; e-mail: <ajtan01@sibs.ac.cn>
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Journal
Proceedings of the National Academy of Sciences