Simulation analysis of the cellulase Cel7A carbohydrate binding module on the surface of the cellulose Iβ
- Univ. of Heidelberg (Germany); Univ. of Tennessee, Knoxville, TN (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
The Family 7 cellobiohydrolase (Cel7A) from Trichoderma reesei consists of a carbohydrate-binding module (CBM) joined by a linker to a catalytic domain. Cellulose hydrolysis is limited by the accessibility of Cel7A to crystalline substrates, which is perceived to be primarily mediated by the CBM. The binding of CBM to the cellulose I fiber is characterized by combined Brownian dynamics (BD) and molecular dynamics (MD) simulations. Our results confirm that CBM prefers to dock to the hydrophobic than to the hydrophilic fiber faces. Both electrostatic (ES) and van der Waals (VDW) interactions are required for achieving the observed binding preference. The VDW interactions play a more important role in stabilizing the CBM-fiber binding, whereas the ES interactions contribute through the formation of a number of hydrogen bonds between the CBM and the fiber. At long distances, an ES steering effect is also observed that tends to align the CBM in an antiparallel manner relative to the fiber axis. Moreover, the MD results reveal hindered diffusion of the CBM on all fiber surfaces. The binding of the CBM to the hydrophobic surfaces is found to involve partial dewetting at the CBM-fiber interface coupled with local structural arrangements of the protein. The present simulation results complement and rationalize a large body of previous work and provide detailed insights into the mechanism of the CBM-cellulose fiber interactions.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1265898
- Journal Information:
- Cellulose, Vol. 21, Issue 2; ISSN 0969-0239
- Publisher:
- Springer
- Country of Publication:
- United States
- Language:
- English
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