Description:
While plant cell wall material is an abundant renewable polymer and has great potential for bio‐fuel production, it is very recalcitrant to hydrolysis due to insolubility and heterogeneity. As a result, invention and optimization of enzymatic processes that process cellulosic biomass to produce monomeric sugar as a fermentable source has been a global focus. Here, we show structural and functional characterization of a novel bi‐functional enzyme that was identified from the rumen of herbivores. This enzyme is unique because it is shown to harbor high xylanase and ferulic acid esterase (FAE) activity within a single polypeptide. The determined crystal structure of the apo‐enzyme and binary complex structure of protein and synthetic substrate provide the basis for rational design and engineering of munti‐functional plant cell wall enzymes. The structures reveal an (á/â)8‐barrel xylanase domain and á/â hydrolase fold ferulic acid esterase domain, linked by carbohydrate binding module (CBM) ‐like folded linker region. Based on the sequence alignment and the conformation of active site, we can postulate a mechanism for plant cell wall hydrolysis.