Submitted to: Protein Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2003
Publication Date: 3/1/2003
Citation: Lee, C.C., Wong, D., Robertson, G.H. 2005. Cloning and characterization of the xyn11a gene from lentinula edodes. Protein Journal. 24(1):21-26.
Interpretive Summary: The world's supply of fossil fuel is steadily being depleted. The only viable alternative source for our fuel and chemical feedstock needs is biomass which is composed of lignocellulose. One of the main components of lignocellulose is hemicellulose. An engineered enzyme that would efficiently hydrolyze the hemicellulose would be very useful for the resulting chemical feedstock product, primarily xylose. In addition, hydrolysis of hemicellulose would increase the accessibility of cellulose, another major component of lignocellulose, to hydrolysis. We have cloned and characterized a novel hemicellulolytic enzyme, xylanase, from Lentinula edodes, commonly referred to as the Shiitake mushroom. This organism was targeted because it grows on fallen logs, so it must secrete all the enzymes necessary to hydrolyze this lignocellulosic substrate. We developed an expression system that will produce active xylanase enzyme and will allow for the screening of mutant gene libraries in future engineering projects to improve xylanase activity.
Technical Abstract: Hemicellulose represents a rich source of biomass that can be converted into useful chemical feedstocks. One of the main components of hemicellulose is xylan, a polymer of xylose residues. Xylanase enzymes that hydrolyze xylan are therefore of great commercial interest. We have cloned a gene (xyn11A) that encodes a 283-amino acid xylanase enzyme from the fungus Lentinula edodes. The enzyme has a pI of 4.6 and belongs to the highly conserved glycosyl hydrolase family 11. The xylanase gene was cloned into a Pichia pastoris expression vector that secretes active enzyme into both solid and liquid media. The optimal pH of the xylanase enzyme was determined to be 4.5.