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Hypocrea jecorina (Trichoderma reesei) Cel7A as a molecular machine: A docking study
Chandrika Mulakala1, Peter J Reilly
1Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa 50011-2230, USA.
Proteins
|July 8, 2005
Summary
Hypocrea jecorina (formerly Trichoderma reesei) Cel7A uses its cellulose-binding domain to feed cellulose chains into its catalytic domain. This molecular machine model explains how the enzyme degrades crystalline cellulose through processive hydrolysis.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Hypocrea jecorina (formerly Trichoderma reesei) Cel7A is a key enzyme in cellulose degradation.
- It possesses a catalytic domain (CD) and a cellulose-binding domain (CBD) linked by a glycosylated region.
- The interaction between these domains and crystalline cellulose is not well understood.
Purpose of the Study:
- To elucidate the molecular mechanism of crystalline cellulose degradation by Hypocrea jecorina Cel7A.
- To propose a model for the interaction between the enzyme's domains and the cellulose substrate.
- To understand the forces involved in processive hydrolysis.
Main Methods:
- Computational docking of cello-oligosaccharides to the CD and CBD.
- Analysis of interaction energies and forces.
- Development of a molecular machine model.
Main Results:
- The CBD acts as a wedge, accessing free chain ends on crystalline cellulose.
- The CBD feeds cellulose chains into the CD active site tunnel.
- Enzyme-substrate interactions generate forces for chain pulling and enzyme translocation.
- Energy for these forces originates from glycosidic bond breakage.
Conclusions:
- A molecular machine model is proposed for Hypocrea jecorina Cel7A action on crystalline cellulose.
- The CBD and CD work synergistically to achieve processive hydrolysis.
- This mechanism explains the enzyme's efficiency in degrading crystalline cellulose.