In another feat of bioengineering, Caltech’s Frances Arnold, the Linus Pauling Professor of Chemical Engineering, Bioengineering and Biochemistry, and her team have created bacteria that can, for the first time, make chemical compounds containing bonds between boron and carbon.
Such boron-carbon bonds came only from the laboratories of chemists and could not be produced by any known life form.
The finding is part of a new wave in synthetic biology, in which living organisms are taught to make chemical compounds needed for pharmaceuticals, agricultural chemicals, and other industrial products.
Last year, Arnold’s team also engineered bacteria to produce molecules with silicon-carbon bonds, called organosilicon compounds, which can be found in everything from pharmaceuticals to semiconductors.
To coax the bacteria into making boron-containing compounds, the scientists used a method pioneered by Arnold in the early 1990s called directed evolution, in which enzymes are evolved in a lab to perform desired functions-such as creating chemical bonds that aren’t found in the biological world.
They mutated the DNA that encodes the protein and then put the mutated DNA sequences into thousands of bacterial cells to see whether the resulting bacteria could create the desired boron-carbon bonds.
The DNA of successful mutant proteins was then mutated again, and the cycle was repeated until the bacteria making the proteins were highly proficient at assembling the boron-carbon compounds.