Protein-based materials have progressed with mechanical characteristics, rivaling the best manmade materials, thanks to Nature. For instance, spider silk is believed to be more strong than steel. However, it is not possible to produce spider silk in bulk. Scientists, however, have now reported a technique that utilizes engineered bacteria for the production of spider silk and other hard-to-manufacture proteins.
“In nature, there are a lot of protein-based materials that have amazing mechanical properties, but the supply of these materials is very often limited,” statedFuzhong Zhang, Ph.D. He is the principal investigator of the project. “My lab is interested in engineering microbes so that we can not only produce these materials, but make them even better.”
Spider silk could be used for numerous purposes(e.g. bulletproof cloth) provided it is produced in sufficient quantities. Spiders make spider silk in small amounts, so scientists have tried engineering bacteria, plants, etc. to make it; however, they are still unable to fully imitate its mechanical properties.
Spider silk proteins are encoded by very lengthy, greatly repetitive arrangements of DNA. When positioned in other organisms, the genes appear to be highly unstable. Zhang and fellow researchers pondered if they could break the protracted sequences into shorter ones that bacteria could manufacture into proteins. They then could be formed into the longer spider silk fiber.
The group led the genes to bacteria, which encoded 2fragments of the spider silk protein, each bordered by a sequence known as a split intein(protein sequences with enzymatic activity). They then opened the bacteria and filtered the small segments of spider silk protein. Mixing them resulted in them joining through ‘glue’ of the split intein sequence, which then cut itself out to produce the original-length protein. When rolled into fibers, the manmade spider silk had all of the characteristics of natural spider silk. Researchers managed to obtain more silk through this process than they did from spiders.
Adding to the applications here on Earth, the bacterial protein production technique could aid during space missions, observesZhang. “NASA is one of our funders, and they are interested in bioproduction,” he stated. “They’re currently developing technologies in which they can convert carbon dioxide into carbohydrates that could be used as food for the microbes that we’re engineering. That way, astronauts could produce these protein-based materials in space without bringing a large amount of feedstocks.”