Web from a bioreactor
A strong and elastic web fiber woven in the laboratory
Marina Astvatsaturyan, Echo of Moscow
The features of the next attempt to recreate this unique natural material are reported by the journal Nature Chemical Biology (Andersson et al., Biomimetic spinning of artificial spider silk from a chimeric minispidroin).
The threads of the web are stronger than steel and more elastic than rubber, these natural properties have been a challenge for bioengineers for many years. Now scientists are proposing a method for large-scale production of spider thread from a hybrid protein, which significantly distinguishes their achievement from previous developments, in particular, transgenic goats that give milk with one of the proteins of the web, as well as yeast and bacterial strains that produce spiderweb proteins due to individual genes embedded in them. The new study is reported by the Live Science portal with reference to the authors of the publication in Nature Chemical Biology, a group from the Swedish University of Agricultural Sciences in Uppsala (Spinning spider silk is now possible).
Previous bioengineered spidroins did not reproduce all the properties of natural spider proteins. Obtained in solutions in small quantities at low concentrations, they stuck together into insoluble lumps. Spiders spin their webs in microscopic spinning tubes, which are located at the ends of spider warts on the spider's abdomen. These tubes open the spider glands located in the abdominal cavity of spiders. The acidity in the spinning tubes varies from slightly alkaline with a pH value of 7.6 to acidic, pH 5.7, and this pH shift contributes to a change in the shape of the protein at the ends, which leads to self-assembly of spider proteins into a web thread on the principle of "key to lock". The spinning tube has a shape tapering to the end and as a result, the fibers of the speedroins pushed through it come out in the form of strands. Swedish researchers decided to reproduce the natural conditions of the spider glands, taking into account the fact that the web proteins of different spider species have different values of acidity and solubility.
The authors combined the spidroin genes of two spider species and created a hybrid spider protein gene (NT2RepCT). He encoded a completely new protein that absorbed the best properties of spidroins from both types of spiders for production in artificial conditions: high solubility and high sensitivity to pH levels. The created genetic construct was embedded in the DNA of the bacterium Escherichia coli, which produced a hybrid protein.
During the cultivation of bacteria, a concentrated solution of spider web protein was obtained, which looked as cloudy and viscous as the secret inside the spider glands. Having passed the culture liquid through a thin glass capillary, the authors obtained 1000 meters of spider fiber from a liter flask. The only drawback of the resulting fiber is that it is less durable than its natural prototype.
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