Reduced type-A carbohydrate-binding module interactions to cellulose I leads to improved endocellulase activity

Area of Science:

• Biochemistry
• Biotechnology
• Enzymology

Background:

• Cost-effective biomass conversion to sugars is limited by nonproductive enzyme binding to cellulose.
• Carbohydrate-binding modules (CBMs) are implicated in this nonproductive binding, but their precise role is unclear.

Purpose of the Study:

• To investigate the relationship between CBM binding affinity and cellulose hydrolysis activity.
• To understand how CBMs influence enzyme interaction with different cellulose allomorphs.

Main Methods:

• Generated mutant CBMs with varied cellulose affinities.
• Assessed enzyme activity of CelE-CBM fusion constructs.
• Utilized quartz crystal microbalance with dissipation for kinetic binding assays.

Main Results:

• Reduced CBM binding affinity to cellulose I correlated with increased endocellulase activity.
• This reduction was linked to higher desorption rates and lower adsorption rates.
• Differences were observed between cellulose I and cellulose III allomorphs.

Conclusions:

• CBMs play a significant role in regulating enzyme-cellulase interactions.
• Optimizing CBM-cellulose interactions can enhance biomass conversion.
• This research provides a foundation for designing improved cellulolytic enzymes.