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Proteins are the most important functional biomolecules in nature with numerous applications in life science research, biotechnology and medicine. So how can they be modified in the most effective way to attain certain desired properties? In the past, the modifications were usually carried out either chemically or via genetic engineering. The team of Professor Arne Skerra from the TUM Chair of Biological Chemistry has now developed a more elegant combined solution: By extending the otherwise universal genetic code, the scientists are able to coerce bacterial cells to produce tailored proteins with synthetic functional groups. To put their idea to the test, they set out to crack a particularly hard nut: The scientists wanted to incorporate a non-natural amino acid at a specific site into a widely used natural protein.
In bioresearch this protein is commonly known as "GFP" (= green fluorescent protein). It emits a bright green glow and stems originally from a jellyfish that uses the protein to make itself visible in the darkness of the deep sea. The team chose a pale lavender coumarin pigment, serving as side chain of a non-natural amino acid, as the synthetic group. The scientists "fed" this artificial amino acid to a laboratory culture of Escherichia coli bacteria the microorganism workhorses of genetic engineering, whose natural siblings are also found in the human intestine. Since the team had transferred the modified genetic blueprints for the GFP to the bacteria including the necessary biosynthesis machinery it incorporated the coumarin amino acid at a very specific site into the fluorescent protein.
This spot in the GFP was carefully chosen, explains Professor Skerra: "We positioned the synthetic amino acid at a very close distance from the fluorescence center of the natural protein." The scientists em
|Contact: Jana Bodicky|
Technische Universitaet Muenchen