Researchers Engineer Catalyst Normally Found in Nature to Achieve Much Greater Efficiency

Achievement date: 
2013
Outcome/accomplishment: 

Researchers at the Center for Biorenewable Chemicals (CBiRC), an NSF-funded Engineering Research Center (ERC) headquartered at Iowa State University, determined precise architectural information about the atoms in a catalyst and then engineered it for greater production efficiency. This engineered variant possesses predictably greater activity than those found in nature.

Impact/benefits: 

The newly engineered enzymes, in combination with strain-engineering strategies, led to a 30-fold increase in pyrone yield. (Pyrones are a class of cyclic chemical compounds, some of which can serve as building blocks for more complex chemical structures.) Pyrone production levels now approach those needed for commercial interest.

Explanation/Background: 

The CBiRC researchers determined the three- dimensional structure at atomic resolution of a pyrone-forming enzyme (see accompanying figure). Knowledge of the precise placement of each atom of the large macromolecular catalyst was then used to engineer the enzyme catalyst for greater efficiency at producing its pyrone product from abundant chemical building blocks available in cells. Using genetic engineering, the team reduced the volume of the active site of pyrone synthase (a synthase is an enzyme that catalyzes a synthesis process through which conversions to more complex products take place); the active site is where all the chemistry associated with pyrone production occurs. The reduction was just the right size for the pyrone product and not too big, as in the natural enzyme. In other words, the team achieved “The Goldilock's Principle.”

In general, CBiRC is focused on ways to produce industrial chemicals from bio-renewable sources. As part of this effort, CBiRC strives to deliver a framework for new bio-based platform chemicals. An emerging example involves pyrone chemicals as well as discoveries in enzyme engineering, microbial engineering, and chemical engineering to deliver a series of bio-based chemical commodities. These advances, illustrated by the catalyst-engineering feat described above, are expected to yield molecules with commercial potential. Also, the time is expected to be relatively short from discovery and enzyme-engineering-based improvements in catalytic efficiency to deployment in production microbes and eventual chemical catalyst transformation.