Molecular dynamics study of carbohydrate binding module mutants of fungal cellobiohydrolases

• The wild-type and mutated CBMs were systematically studied by docking analysis.
• A mutation affected the binding affinities of the CBMs to the cellulose surface.
• A mutation also affected the directional preferences with respect to cellulose.
• The affinities predicted for some of the CBMs were qualitatively in agreement with the observed adsorption behaviors of the CBMs.
• The CBM mutants changed the interior hydrogen bond as well as those with cellulose.

The present study reports the systematic survey of binding free energies at the interface between a carbohydrate-binding module (CBM) and a cellulose Iα crystal model using molecular dynamics’ calculations. The two wild type CBMs (Cel7A CBM and Cel6A CBM) have been studied, as well as seven mutants of Cel7A CBM. A comparison of the experimental data for the two wild type and the four mutants CBMs (i.e., Y5A, Y5W, N29A, and Q34A) revealed that the interaction energies of Y5W and Q34A were larger than that of the wild type Cel7A CBM, whereas Y5A and N29A gave smaller values. These predicted values of the interaction energies were compared with the results observed for the adsorbing behaviors of the CBMs.

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