Despite the fact that silicon makes up about 30 percent of the Earth’s crust, it plays no role in the creation of organic life, and no known organisms are able to incorporate it into the carbon chains that make up their biological material. However, after performing a little genetic trickery, scientists have finally got living cells to bind silicon and carbon together, creating new opportunities for industrial and pharmaceutical production.
Silicon-containing compounds have a range of applications, and are used to create industrial catalysts, superconductors, and medicinal products. However, creating these materials can be costly and often requires the use of highly expensive trace metals.
Researchers from the California Institute of Technology therefore decided to seek out alternative methods of producing these materials, turning to nature for inspiration. First, they sifted through databases in search of organic enzymes that are capable of catalyzing silicon, and identified an iron-based enzyme that helps to bind silicon with hydrogen in a bacteria called Rhodothermus marinus, found in underwater hot springs.
They then synthesized the gene for this protein and inserted it into E.coli cells, which caused the bacteria to bind silicon and carbon when fed certain silicon-containing ingredients. However, reporting their findings in the journal Science, the study authors write that the efficiency of this catalyst was not particularly impressive.
They therefore tweaked the enzyme’s genetic code slightly, adding in a few mutations that they suspected would create an active site to catalyze silicon-carbon binding. Lo and behold, their suspicions turned out to be accurate, as the altered protein was able to bind the two elements with superb efficiency, producing a yield 15 times higher than that of the most advanced industrial catalysts.
In their write-up, the researchers claim their findings “affirm the notion that nature’s protein repertoire is highly evolvable and poised for adaptation,” adding that “with only a few mutations, existing proteins can be repurposed to efficiently forge chemical bonds not found in biology and grant access to areas of chemical space that living systems have not explored.”