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A High Throughput Screen for Biomining Cellulase Activity from Metagenomic Libraries
Published on: February 1, 2011
Advanced evolutionary molecular engineering to produce thermostable cellulase by using a small but efficient library.
1Biotechnology Laboratory, Toyota Central R&D Laboratories, Inc., Yokomichi, Nagakute, Aichi, Japan.
Protein Engineering, Design & Selection : PEDS
|October 24, 2012
Summary
Engineered cellobiohydrolase II (CBH2) variants from Phanerochaete chrysosporium exhibit enhanced thermostability. The Mall4 variant retained activity over 72 hours at 50°C, demonstrating successful molecular engineering for industrial applications.
Area of Science:
- Biotechnology
- Enzyme Engineering
- Molecular Biology
Background:
- Cellobiohydrolase II (CBH2) is crucial for cellulose degradation.
- Improving enzyme thermostability is key for industrial biocatalysis.
- Phanerochaete chrysosporium CBH2 is a mesophilic enzyme with limited thermal stability.
Purpose of the Study:
- To engineer thermostable cellulase variants of CBH2 from P. chrysosporium.
- To identify and accumulate advantageous mutations for enhanced thermal stability.
- To evaluate the performance of engineered variants under thermal stress.
Main Methods:
- Comparative sequence analysis of fungal CBH2 catalytic domains.
- Site-directed mutagenesis guided by consensus sequences.
- Cell-free translation system for variant screening.
- Directed evolution by accumulating beneficial mutations.
Main Results:
- Identified 45 differing positions between P. chrysosporium CBH2 and thermophilic CBH2 consensus sequences.
- Discovered advantageous mutations for thermostability with higher frequency than random libraries.
- Developed the Mall4 variant with 15 beneficial mutations, showing significantly improved thermostability.
- Mall4 retained wild-type specific activity and >72h stability at 50°C, unlike wild-type PcCBH2.
Conclusions:
- Advanced evolutionary molecular engineering effectively enhances enzyme thermostability.
- The developed Mall4 variant demonstrates superior thermal stability for potential industrial use.
- The employed evolutionary process rapidly and ideally achieved improved thermostability in PcCBH2.
