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A bacterial GH6 cellobiohydrolase with a novel modular structure
Liliana Cerda-Mejía1, Susana Valeria Valenzuela1, Cristina Frías1
1Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
Applied Microbiology and Biotechnology
|January 26, 2017
Summary
This study characterizes Cel6D, a novel cellobiohydrolase from Paenibacillus barcinonensis. Its unique structure and synergistic activity with other cellulases show promise for breaking down cellulose.
Area of Science:
- Biochemistry
- Enzymology
- Protein Engineering
Background:
- Cellulose degradation is crucial for biofuel production and biomass conversion.
- Glycosyl hydrolases, particularly cellobiohydrolases, play a key role in breaking down cellulose.
- Paenibacillus barcinonensis produces a range of enzymes for cellulose deconstruction.
Purpose of the Study:
- To characterize the novel cellobiohydrolase Cel6D from Paenibacillus barcinonensis.
- To elucidate the structure-function relationship of Cel6D's modular domains.
- To evaluate the synergistic potential of Cel6D with other cellulases.
Main Methods:
- Purification and enzymatic activity assays of Cel6D and its truncated/mutant derivatives.
- Kinetic parameter determination (K_m, V_max) on phosphoric acid swollen cellulose (PASC).
- Analysis of cooperative activity with endoglucanase Cel9B.
Main Results:
- Cel6D exhibits cellobiohydrolase activity, releasing cellobiose from cellulose.
- The fibronectin III-like domain (Fn3) and cellulose-binding domain (CBM3b) are essential for full activity.
- Catalytic residues are critical for enzyme function, as shown by inactive mutants.
- Cel6D shows significant synergy with Cel9B on crystalline cellulose.
Conclusions:
- Cel6D possesses a unique modular architecture with essential Fn3 and CBM3b domains.
- The enzyme's catalytic residues are vital for its function.
- Cel6D's synergistic action with Cel9B enhances crystalline cellulose hydrolysis.
- Cel6D is a valuable enzyme for cellulosic substrate depolymerization and native cellulose deconstruction.
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