Harnessing glycosylation to improve cellulase activity.

Cellulases and hemicellulases are responsible for the turnover of plant cell wall polysaccharides in the biosphere, and thus form the foundation of enzyme engineering efforts in biofuels research. Many of these carbohydrate-active enzymes from filamentous fungi contain both N-linked and O-linked glycosylation, the extent and heterogeneity of which depends on growth conditions, expression host, and the presence of glycan trimming enzymes in the secretome, all of which in turn impact enzyme activity. As the roles of glycosylation in enzyme function have not been fully elucidated, here we discuss the potential roles of glycosylation on glycoside hydrolase enzyme structure and function after secretion. We posit that glycosylation, instead of hindering cellulase engineering, can be used as an additional tool to enhance enzyme activity, given deeper understanding of its molecular-level role in biomass deconstruction.