Molecular insights into inhibiting effects of lignin on cellulase investigated by molecular dynamics simulation

Abstract

The hydrolysis of lignocellulose into fermentable monosaccharides using cellulases represents a critical stage in lignocellulosic bioconversion. However, the inactivation of cellulase in the presence of lignin is attributed to the high cost of biofinery. To address this challenge, a comprehensive investigation into the structure–function relationship underlying lignin-driven cellulase inactivation is essential. In this study, molecular docking and molecular dynamics (MD) simulations were employed to explore the impacts of lignin fragments on the catalytic efficiency of cellulase at the atomic level. The findings revealed that soluble lignin fragments and cellulose could spontaneously form stable complexes with cellulase, indicating a competitive binding scenario. The enzyme’s structure remained unchanged upon binding to lignin. Furthermore, specific amino acid residues have been identified as involved in interactions with lignin and cellulose. Hydrophobic interactions were found to dominate the binding of lignin to cellulase. Based on the mechanisms underlying the interactions between lignin fragments and cellulase, decreased hydrophobicity and change in the charge of lignin may mitigate the inhibition of cellulase. Furthermore, site mutations and chemical modification are also feasible to improve the efficiency of cellulase. This study may contribute valuable insights into the design of more lignin-resistant enzymes and the optimization of lignocellulosic pretreatment technologies.

Communicated by Ramaswamy H. Sarma

Keywords:

• Lignocellulose
• lignin
• cellulase
• molecular docking
• MD simulations

Disclosure statement

No conflict of interest exists in the submission of this manuscript, and manuscript is approved by all authors for publication. The work described is original research that has not been previously published and is not being considered for publication elsewhere, in whole or in part. All authors listed have approved the attached manuscript.

Additional information

Funding

This work was supported by the Natural Science Basic Research Plan in Shaanxi Province of China and Natural Science Foundation of Shaanxi University of Science & Technology under Grant 2021JQ-537.