ARS | Publication request: Designer xylanosomes: protein nanostructures for enhanced xylan hydrolysis.

Submitted to: Biomacromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2012
Publication Date: May 4, 2012
Citation: Mcclendon, S.D., Mao, Z., Shin, H., Wagschal, K.C., Chen, R.R. 2012. Designer xylanosomes: protein nanostructures for enhanced xylan hydrolysis.. Biomacromolecules. 167: 385-411.

Interpretive Summary: Hemicellulose is a major component of the woody part of plants, and represents a significant renewable source of chemical energy. However, it is necessary to break the hemicellulose down into simpler components, that are then converted by other processes to a more useable form of the energy, e.g. bioethanol, biobutanol, or to value-added products. To deconstruct hemicellulose enzymatically requires a suite of different enzymes, including arabinofuranosidases, xylanases, and ferulic acid esterases. Breakdown of hemicellulose can also facilitate the breakdown of the cellulose portion of biomass. We describe here the design, construction, and application of multi-functional, self-assembling biocatalysts for targeted xylan hydrolysis, termed xylanosomes, that may find use in the breakdown of hemicellulose and cellulose.

Technical Abstract: This work is the first report of the successful design, construction, and application of multi-functional, self-assembling biocatalysts for targeted xylan hydrolysis, termed xylanosomes. Using the architecture of cellulosomes found in some anaerobic cellulolytic microbes, four different xylanosomes were designed and constructed using recombinant DNA and molecular cloning techniques. Each xylanosome was composed of two hemicellulases and tested on wheat arabinoxylan or destarched corn bran for enzymatic hydrolysis. After a 24 hour-incubation, soluble sugars released from arabinoxylan increased up to 30% with xylanosomes containing a xylanase and bi-functional arabinofuranosidase/xylosidase over the corresponding free, unstructured enzymes. Furthermore, xylanosomes with a xylanase and ferulic acid esterase removed between 15 – 20% more ferulic acid from wheat arabinoxylan. Xylanosomes also showed synergy with cellulases on destarched corn bran, suggesting a possible use of these nanostructures in cellulose hydrolysis.