Transgenic Silk Moths to Produce Spider Silk

摘要

The unusual combination of strength and extensibility of the Nephila clavipes spider dragline silk greatly suipasses all currently known high- performance synthetic materials. Together with the fact that silk is biocompatible and biodegradable, this natural polymer constitutes a very promising fiber for novel applications including use in bullet-and explosion- proof clothing and highly resistant surgical thread. Yet, massive production of this fiber from natural sources is not feasible so far. Other alternatives like production of the protein that yields same or similar mechanical properties of dragline silk in microorganisms or mammalian cells, in spinning fibers from concentrated protein solutions, have failed or are inefficient. Currently, silk is produced from the cocoon of the silk moth Bombyx mori; however, this silk has about one-tenth the strength and flexibility of Nephila clavipes silk. The goal of this proposal is to develop a transgenic silk moth able to produce Nephila clavipes dragline-like silk. In order to do this, a chimeric gene called Spidrofibroin (SpF) have been constructed. SpF combined the repetitive domains of spider dragline silk with the N- and C- terminal domains of the Bombyx mori silk gene, Fibroin-H (Fib-H). Various SpF genes have been cloned under the promoter of the Fib-H gene in pBac vectors and used to generate silk moth embryos. The silk fibers spun in the transgenic silk moth cocoons are being analyzed with respect to expression of SpF and mechanical properties of the resulting fiber. Since the SpF variants will have all the necessary elements for expression, transport and assembly into the silk fiber of Bombyx mori as Fib-H does, we believe that SpF will compete with Fib-H for its assembly into the silk fiber.