Functional and structural analysis of HviXyn11D xylanase from Hypocrea virens and its application to xylooligosaccharide production from agro-food by-products.

Abstract

Xylanases play important roles in lignocellulosic biomass degradation and have broad industrial applications. The discovery of new xylanases expands our understanding of these enzymes and provides new opportunities for industrial applications. This study performed biochemical and structural characterization of the xylanase Xyn11D from Hypocrea virens (HviXyn11D) and evaluated its potential for XOS production from agro-food by-products. HviXyn11D exhibited optimal hydrolytic activity against beechwood xylan at 50 °C and pH 5. Its enzymatic activity was enhanced in the presence of the biomass-derived compounds furfural, 5-hydroxymethylfurfural, and vanillin. The crystal structure of HviXyn11D exhibited a typical β-jelly roll fold and showed a unique substrate-binding cleft compared with homologous xylanases, adopting a closed conformation of the substrate-binding cleft with rigid thumb and finger domains. Molecular dynamics simulations demonstrated that higher temperatures increased the flexibility of the thumb and finger domains, leading to an open conformation of the substrate-binding cleft. Recombinant HviXyn11D enabled the hydrolysis of agro-biomass by-products derived from rice straw, corn cob, and sugarcane bagasse, resulting in successful XOS production. Together, these findings highlight the potential industrial applications of HviXyn11D in biomass degradation and provide new insights into the molecular and structural functions of HviXyn11D and the GH11 xylanase family.