In silico Insights into Acetylxylan Esterase Diversity: Decoding its Role in Hemicellulose Deacetylation for Enhanced Biofuels Generation

The enzymatic hydrolysis of hemicelluloses and acetyl groups stands as a cornerstone in biofuels production, with profound implications for bioethanol and bio-hydrogen generation. Emphasizing the resilience of hemicellulose and cellulose, resilient biopolymers that comprise biomass, this study delves into the in silico exploration of acetylxylan esterase (EC 3.1.1.72), a pivotal member of carboxylic esterase hydrolases (EC 3.1.1), to unveil its crucial role in the deacetylation of xylans and xylo-oligosaccharides.

Employing a multidimensional approach, we meticulously scrutinized three-dimensional structures, encompassing X-ray crystallography-determined and AlphaFold-predicted models of acetylxylan esterase. Microorganisms under investigation include Trichoderma reesei, Acetivibrio thermocellus, Cellvibrio japonicus, Flavobacterium johnsoniae, Thermoanaerobacterium saccharolyticum, Clostridium cellulovorans, and Caldicellulosiruptor saccharolyticus.

Molecular docking and dynamic simulations were conducted to unravel the intricate interactions between acetylxylan esterase and a diverse array of chemically modified xylopyranoside ligands. These ligands, embodying various acetylation patterns, were derived from xylopyranoside, a resilient component of hemicellulose. Significantly, the strategic cross-referencing of targets from ExplorEnz, BRENDA, UniProtKB, RCSB-PDB, and PubChem databases played a pivotal role in enriching the investigation.

This exploration provides profound insights into the substrate specificity of acetylxylan esterase, underscoring its potential role in the deacetylation of diverse substrates. Furthermore, the study offers a comprehensive analysis of biotechnologically relevant applications, spanning industrial-scale enzyme production, cellulolytic and ethanologenic capabilities, and biohydrogen production, intricately linked to the investigated variants of acetylxylan esterase.

Funding and acknowledgments: This research was funded by the Romanian Ministry of Research, Innovation and Digitization through the NUCLEU Program, Contract no. 20N/05.01.2023, Project PN 23 15 04 01 (BioVal). We acknowledge for institutional support the Program 1—Development of the national research and development system and Subprogram 1.1. Institutional performance—Projects to finance excellence in RDI, Contract No. 19PFE/30.12.2021.