Animal's genetic code redesigned

Just 20 amino acids are used in natural living organisms, assembled in different combinations to make the tens of thousands of different proteins needed to sustain life. But Sebastian Greiss and Jason Chin have re-engineered the nematode worm's gene-reading machinery to include a 21st amino acid, not found in nature.

At Scripps, researchers showed in a paper in PNAS how one of those three letter words could be re-assigned, so that cells would read it as an instruction to incorporate an unnatural amino acid, one not normally found in living organisms. But that was in the bacterium E. coli; until now, no one had succeeded in doing the same in a whole animal.

So far it is just a proof of principle - the artificial protein that is produced in every cell of the nematode worm's tiny body contains a fluorescent dye that glows cherry red under ultraviolet light. If the genetic trick failed, there would be no glow.

But Dr Chin says any artificial amino acid could be chosen to produce specific new properties. Dr de Bono suggests the approach could now be used to introduce into organisms designer proteins that could be controlled by light.

Metabolism in reverse: Making biofuels at full-throttle pace

Researchers unveiled a new method for rapidly converting simple glucose into biofuels and petrochemical substitutes. In a paper published online in Nature, Rice's team described how it reversed one of the most efficient of all metabolic pathways -- the beta oxidation cycle -- to engineer bacteria that produce biofuel at a breakneck pace.

On a cell-per-cell basis, the bacteria produced the butanol, a biofuel that can be substituted for gasoline in most engines, about 10 times faster than any previously reported organism. "That's really not even a fair comparison because the other organisms used an expensive, enriched feedstock, and we used the cheapest thing you can imagine, just glucose and mineral salts."

Gonzalez's team reversed the beta oxidation cycle by selectively manipulating about a dozen genes in E. coli. They also showed that selective manipulations of particular genes could be used to produce fatty acids of particular lengths, including long-chain molecules like stearic acid and palmitic acid, which have chains of more than a dozen carbon atoms.

"This is not a one-trick pony," Gonzalez said. "We can make many kinds of specialized molecules for many different markets. We can also do this in any organism. Some producers prefer to use industrial organisms other than E. coli, like algae or yeast. That's another advantage of using reverse-beta oxidation, because the pathway is present in almost every organism."

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