Part:BBa_K4247015

Aneroin_middle

This part is the middle of the aneroin protein (composite part BBa_K247017). The sequence of aneroin has multiple repetitions of the motif GPGNTGYPGQ (with seldom variations) and thus, was difficult to synthesise due to extreme repetitiveness. As part of our collection, Aneroin_middle (BBa_K247015) can be linked to Aneroin_Nt (BBa_K247014) and Aneroin_Ct (BBa_K247016) to form the composite part Aneroin (BBa_K247017). Aneroin contains some of the typical motifs of collagens and spider silk, it can be therefore spun into a fibre.

Usage and Biology

Silk proteins are becoming increasingly popular fibres for biomaterials in many biotechnological fields, from medicine to common consumables. In 2013, Yang and colleagues discovered a new silk-like protein in the sea anemone Nematostella vectensis. This sea-star anemone lives along the coasts of England and the USA, and has been used for a long time as a model organism for the phylum Cnidaria. The protein was an hypothetical protein found in the model genome when Yang et al. (2013) discovered it. It’s characterised by its localisation in the nematocysts of the tentacles (the harpoon-like weapons of Cnidarians) and by the repetitive motif GPGNTGYPGQ.

The protein has high levels of glycine and proline, the GXX repeat motif of collagens and the GPGXX repeat of spider silks, suggesting its involvement with prey capture and potential for fiber formation. Considerinng its properties, we exploited it to include it in a biocomposite material to substitute nylon in fishing nets, but it has also been used as part of artificial heart valves.

Figure 1: (a) N. vectensis. (b) Protein sequence. (c,d) N. vectensis images before (c) and after (d) stimulus. Immunohistochemical analyses of N. vectensis with aneroin-specific antibody (e) and purified normal rabbit IgG as a negative control (f). From Yang, Y., Choi, Y., Jung, D., Park, B., Hwang, W., Kim, H. and Cha, H., 2013. Production of a novel silk-like protein from sea anemone and fabrication of wet-spun and electrospun marine-derived silk fibers. NPG Asia Materials, 5(6), pp.e50-e50.

Figure 2: Wet spinning of aneroin fibers: (a) 30KDa aneroin fibers in solution. (b) SEM of wet-spun aneroin-30K fiber surfaces and a breakpoint. (c) Aneroin-30K fiber after spinning. (d) Stress-strain curves of aneroin-30K and aneroin-60K fibers.