(490c) Engineering More Effective Catalysts for Unnatural Allomorphs of Cellulose

Challenges encountered during the conversion of biomass to biofuels are critically linked to the physical properties of the feedstock.  Crystalline cellulose exists in various allomorphic states some of which are not found to occur naturally.  A better understanding of unnatural cellulose allomorphs and their biodegradation will improve the efficiency of next-generation extractive ammonia based pretreatments. However, very little is known about how cellulases interact with such unnatural cellulosic allomorphs. We explore the interactions of various cellulolytic enzymes and their individual carbohydrate binding modules (CBMs) with cellulose allomorphs to gain insight into the mechanism of cellulose deconstruction.  Interactions responsible for stability and reactivity of cellulose are incorporated into computational models, both at the atomistic and coarse-grained levels. These computational models are used to understand and interpret experimental measurements that have revealed that both Type-A and Type-B CBMs (known to target crystalline and amorphous cellulose, respectively) have reduced affinity for non-native cellulose allomorphs (like cellulose III) compared to untreated cellulose (like cellulose I). Our multi-scale computational approach coupled with experiments provides a rational basis for engineering both efficient pretreatment processes and biocatalysts for degradation of cellulose to biofuels.