Sunday, March 15, 2009

Improved synthetic biology for Artemisinin....


We know that Artemision, is a drug to treat multi-drug resistant strains of falciparum malaria. And also fermenting artemisinin via engineered microbes, such as yeast, can be done at far lower costs than extracting the drug from Artemsisia annua , the sweet wormwood tree, making microbial-based artemisinin a much cheaper but equally effective treatment. However the cost of extracting artemisinin from wormwood trees, which only produce the drug under a narrow set of agricultural and climatological conditions or manufacturing it entirely through chemical synthesis is too high. This encouraged Dr. Keasling and his group to undertake this research and are succesful in achieving an improved method, where in the cost will drastically down. And this research is also of great important by the fact that, the same method can be elaborated to make biofuels.

In 2003, they reported their first success. By transplanting genes from yeast and from the sweet wormwood tree into E. coli bacteria and then bypassing the E. coli's metabolic pathway and engineering a new one based on the mevalonate pathway in yeast, they were able to induce the bacteria to produce amorphadiene, a chemical precursor to artemisinin. Even though the yields were low, they achieved one more significance by res using the re-synthesis and other techniques to improve the yield of amorphadiene in E. coli by a million fold. As the conversion of artemisinic acid to artemisinin in high yields are already known, this finding is of great importance.

The most significant part of their reserach is creating a new metabolic pathway in the yeast, similar to the one created in E. coli, then introduced bacterial and wormwood genes into the yeast's DNA that interacted with the yeast's own genes to produce amorphadiene. Finally, they cloned the gene from the wormwood tree that produces the enzyme P450, which the plant uses to convert amorphadiene to artemisinic acid, and expressed it in the amorphadiene-producing yeast strain. And the group wants to use the same technology to make biofuels.... Congrats Dr.Jay D. Keasling...

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