SPIDER SILK

Humans and silk have been intertwined together for a long time now. We have seen it around nearly everywhere, be it in your clothes or be it from Spiderman’s web shooters! This silk has immense potential hidden in its threads. We are all familiar with silkworm silk. It’s a well­studied and developed industry. What we are concentrating on however is spider silk. Spider silk has many applications. Its unique properties of strength, elasticity and well as being lightweight allow it to be an excellent biomaterial. It can beused to forge artificial tendons and ligaments, or even bridge cables. It’s the stuff that can be used to make air bags, cords for parachute or even body armour. Along with this, spider silk has low immunogenicity, thus making it an ideal candidate for biomedical applications such as drug delivery systems and scaffolds for tissue engineering. Cultivating silkworms may not be such a headache but these spiders put up a lot of fight. So we need some way in which this can be done on an industrial scale.

BACTERIAL SILK

As we are all aware, the microbes that grow on everything around us can grow at amazing rate. Not only that, but they can be made to synthesize proteins of our interest with a little genetic tweaking. This brings us to our project. We aim at synthesizing recombinant spider silk protein (MaSp2) in E. coli along with a system to effectively deliver it outside the cell. There have been advances in synthesizing spider silk in bacteria. Some of them by previous iGEM teams themselves. But the successful ideas have involved lysis of the bacterial cells to get to the protein. We would like to combine one of these successful efforts with a secretion system. This will allow us to produce the silk protein, and then reuse the cells for more of the same.

OUR IDEA

Our idea hinges upon the use of a site specific retroviral protease. We aim at synthesizing recombinant spider silk protein (MaSp2) in E. coli and anchoring it to the outer cell membrane, followed by the cleavage of the same using a HIV1 aspartyl protease. The silk protein will be fused to a fragment of OmpA protein that will display it on outer surface of the E. coli. A HIV protease cleavage site will be introduced between the OmpA fragment and the silk protein assembly. A second construct containing the cleavage site and the HIV protease will be fused to the OmpA fragment. Induction of the second protein construct will initiate cleavage by the protease in cis that will release the protease and allow it to cleave in trans and release the spider silk protein.