Team Discovers Enzyme Domains that Dramatically Improve Performance

(Phys.Org/ National Renewable Energy Laboratory) It was more than 10 years in the making, but when it came to uncovering the secrets of the molecular structure of enzymes, perseverance paid off. By studying and comparing the workhorse cellulose-degrading enzymes of two fungi, researchers from the Energy Department's National Renewable Energy Laboratory (NREL) have pinpointed regions on these enzymes that can be targeted via genetic engineering to help break down cellulose faster.

Newly published in Nature Communications, "Engineering enhanced cellobiohydrolase activity" describes NREL's long-running study of the fungal cellobiohydrolases (CBHs)—enzymes that use hydrolysis as their main chemistry to degrade cellulose—Trichoderma reesei (TrCel7A) and Penicillium funiculosum (PfCel7A).

In both nature and industrial processes, enzymes from this family are among the most significant enzymes for breaking down cellulose. A projected 2,000-ton-per-day cellulosic ethanol plant could potentially use up to 5,000 tons of enzyme per year, and half of that enzyme cocktail could be from this enzyme family.

The discovery unfolded as NREL took a close look at the similarities between TrCel7A and PfCel7A and then worked to isolate the differences. Both enzymes have a three-domain architecture: the carbohydrate binding molecule that attaches it to cellulose; the catalytic domain that breaks down cellulose; and the link that connects these two domains together. The research team then conducted domain swapping experiments by creating a chimera library, which is a collection of mutant enzymes created from the two parent enzymes. READ MORE Abstract (Nature)