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Clostridium Thermocellum CbhA- Amino acid sequence modified for enhanced catalytic activity in the saccharification of cellulose

National Renewable Energy Laboratory

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Technology Marketing Summary

The efficient action of cellulases to release fermentable sugars from biomass cellulose is an important step in making biomass-derived products economically viable. Despite efforts to engineer cellulases with significantly improved activities, few successes have been demonstrated.  Prior cellulase engineering has focused upon screening small sets of rationally guided mutations for higher thermal stability and subsequent modest gains in activity at higher conversion temperatures. Significant activity improvement in processive cellulase enzymes on realistic substrates at industrially relevant enzyme loadings and substrate conversion levels remains to be demonstrated. 

Description

Inventors at NREL have engineered dramatically improved cellulosomal cellulases (e.g., C. thermocellum CbhA) by exchanging domains with other cellulases to form chimeric polypeptides. In particular, exchanging linker domains in the chimeric polypeptides resulted in an increase in cellulase activity when compared with the wild-type polypeptides.  The high activity and high intramolecular synergy displayed by the chimeric cellulases also demonstrates the promise of enhancing the activity of cellulases by linking catalytic domains not combined in nature.

CbhA is one of the key cellulosomal cellulases in the C. thermocellum cellulosome system. The improvements in activity exhibited in chimeras by substituting the long linker from C. bescii CelA demonstrates the potential of this new approach exploiting modular cooperation to enhance activity of a large cellulosomal cellulase, but also supports applying this new approach to improvement of other multimodular cellulases. The high activity and high intramolecular synergy displayed by the chimeric cellulases demonstrates the promise of enhancing the activity of cellulases by linking catalytic domains not usually combined in nature.

Benefits
  • Increased cellulase activity
  • Roadmap to further biomass modification
  • Increased thermal stability
Applications and Industries
  • Advanced biofuels and bio-products
  • Enhanced cellulases
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Patent 8,993,276
Patent
8,993,276
CHIMERIC ENZYMES WITH IMPROVED CELLULASE ACTIVITIES
Nucleic acid molecules encoding chimeric cellulase polypeptides that exhibit improved cellulase activities are disclosed herein. The chimeric cellulase polypeptides encoded by these nucleic acids and methods to produce the cellulases are also described, along with methods of using chimeric cellulases for the conversion of cellulose to sugars such as glucose.
National Renewable Energy Laboratory 03/31/2015
Issued
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
NREL ROI 12-33DevelopmentAvailable01/06/201401/06/2014

Contact NREL About This Technology

To: Eric Payne<Eric.Payne@nrel.gov>