Biology textbooks declare that proteins are made from only 20 naturally occurring amino acids, but scientists report that they have modified E. coli bacteria so they can create and process an extra amino acid.
The study is reported in the Jan. 29 edition of the Journal of the American Chemical Society, and was posted to the journal�s Web site on Jan. 4. Lead author is Peter Schultz, a chemistry professor at the Scripps Research Institute in La Jolla, Calif.
Why create an alien bacterium? The research team says the organism could be used as a research tool.
"Why did life settle on 20 amino acids?" said Ryan Mehl, a Scripps researcher who is now on the faculty of Franklin & Marshall College in Lancaster, Pa. "Would more amino acids give you a better organism one that could more effectively adapt if placed under selective pressure?"
The research team manipulated a chunk of genetic code known as a stop codon to incorporate the 21st amino acid, known as p-aminophenylalanine or pAF.
"This bug is self-sufficient; it can make, load and incorporate the new amino acid in the emerging protein all on its own," Mehl said. "It's a bona fide unnatural organism now. Essentially, this bacterium can be added to a minimal media (salts and a basic carbon source) and it�s able to do the rest."
In the future, organisms could be modified to process synthetic amino acids that have therapeutic value. But what about the prospects for mutants wreaking havoc in the wild? Not to worry, the researchers say: The bacteria�s ability to synthesize the amino acid leucine has been crippled "to avoid any risk that the organism could propagate outside a controlled lab setting," said Scripps' Christopher Anderson.
Hmm... That sounds eerily like the fail-safe strategy that went awry in "Jurassic Park." Take a look at the news release, delve into the technical background if you�re so inclined, and let me know what you think.